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1.  Epidemiological Pathology of Dementia: Attributable-Risks at Death in the Medical Research Council Cognitive Function and Ageing Study 
PLoS Medicine  2009;6(11):e1000180.
Researchers from the Medical Research Council Cognitive Function and Ageing Neuropathology Study carry out an analysis of brain pathologies contributing to dementia, within a cohort of elderly individuals in the UK who agreed to brain donation.
Dementia drug development aims to modulate pathological processes that cause clinical syndromes. Population data (epidemiological neuropathology) will help to model and predict the potential impact of such therapies on dementia burden in older people. Presently this can only be explored through post mortem findings. We report the attributable risks (ARs) for dementia at death for common age-related degenerative and vascular pathologies, and other factors, in the MRC Cognitive Function and Ageing Study (MRC CFAS).
Methods and Findings
A multicentre, prospective, longitudinal study of older people in the UK was linked to a brain donation programme. Neuropathology of 456 consecutive brain donations assessed degenerative and vascular pathologies. Logistic regression modelling, with bootstrapping and sensitivity analyses, was used to estimate AR at death for dementia for specific pathologies and other factors. The main contributors to AR at death for dementia in MRC CFAS were age (18%), small brain (12%), neocortical neuritic plaques (8%) and neurofibrillary tangles (11%), small vessel disease (12%), multiple vascular pathologies (9%), and hippocampal atrophy (10%). Other significant factors include cerebral amyloid angiopathy (7%) and Lewy bodies (3%).
Such AR estimates cannot be derived from the living population; rather they estimate the relative contribution of specific pathologies to dementia at death. We found that multiple pathologies determine the overall burden of dementia. The impact of therapy targeted to a specific pathology may be profound when the dementia is relatively “pure,” but may be less impressive for the majority with mixed disease, and in terms of the population. These data justify a range of strategies, and combination therapies, to combat the degenerative and vascular determinants of cognitive decline and dementia.
Please see later in the article for the Editors' Summary
Editors' Summary
Losing one's belongings and forgetting people's names is often a normal part of aging. But increasing forgetfulness can also be a sign of dementia, a group of symptoms caused by several disorders that affect the structure of the brain. The commonest form of dementia is Alzheimer disease. In this, protein clumps called plaques and neurofibrillary tangles form in the brain and cause its degeneration. Vascular dementia, in which problems with blood circulation deprive parts of the brain of oxygen, is also common. People with dementia have problems with two or more “cognitive” functions—thinking, language, memory, understanding, and judgment. As the disease progresses, they gradually lose their ability to deal with normal daily activities until they need total care, their personality often changes, and they may become agitated or aggressive. Dementia is rare before the age of 65 years but about a quarter of people over 85 years old have dementia. Because more people live to a ripe old age these days, the number of people with dementia is increasing. According to the latest estimates, about 35 million people now have dementia and by 2050, 115 million may have the disorder.
Why Was This Study Done?
There is no cure for dementia but many drugs designed to modulate specific abnormal (pathological) changes in the brain that can cause the symptoms of dementia are being developed. To assess the likely impact of these potentially expensive new therapies, experts need to know what proportion of dementia is associated with each type of brain pathology. Although some brain changes can be detected in living brains with techniques such as computed tomography brain scans, most brain changes can only be studied in brains taken from people after death (post mortem brains). In this study, which is part of the UK Medical Research Council Cognitive Function and Ageing Study (MRC CFAS), the researchers look for associations between dementia in elderly people and pathological changes in their post mortem brains and estimate the attributable-risk (AR) for dementia at death associated with specific pathological features in the brain. That is, they estimate the proportion of dementia directly attributable to each type of pathology.
What Did the Researchers Do and Find?
Nearly 20 years ago, the MRC CFAS interviewed more than 18,000 people aged 65 years or older recruited at six sites in England and Wales to determine their cognitive function and their ability to deal with daily activities. 20% of the participants, which included people with and without cognitive impairment, were then assessed in more detail and invited to donate their brains for post mortem examination. As of 2004, 456 individuals had donated their brains. The dementia status of these donors was established using data from their assessment interviews and death certificates, and from interviews with relatives and carers, and their brains were carefully examined for abnormal changes. The researchers then used statistical methods to estimate the AR for dementia at death associated with various abnormal brain changes. The main contributors to AR for dementia at death included age (18% of dementia at death was attributable to this factor), plaques (8%), and neurofibrillary tangles (11%) in a brain region called the neocortex, small blood vessel disease (12%), and multiple abnormal changes in blood vessels (9%).
What Do These Findings Mean?
These findings suggest that multiple abnormal brain changes determine the overall burden of dementia. Importantly, they also suggest that dementia is often associated with mixed pathological changes—many people with dementia had brain changes consistent with both Alzheimer disease and vascular dementia. Because people with dementia live for variable lengths of time during which the abnormal changes in their brain are likely to alter, it may be difficult to extrapolate these findings to living populations of elderly people. Furthermore, only a small percentage of the MRC CFAS participants have donated their brains so the findings of this study may not apply to the general population. Nevertheless, these findings suggest that the new therapies currently under development may do little to reduce the overall burden of dementia because most people's dementia involves multiple pathologies. Consequently, it may be necessary to develop a range of strategies and combination therapies to deal with the ongoing dementia epidemic.
Additional Information
Please access these Web sites via the online version of this summary at
The US National Institute on Aging provides information for patients and carers about forgetfulness and about Alzheimer disease (in English and Spanish)
The US National Institute of Neurological Disorders and Stroke provides information about dementia (in English and Spanish)
The UK National Health Service Choices Web site also provides detailed information for patients and their carers about dementia and about Alzheimer disease
MedlinePlus provides links to additional resources about dementia and Alzheimer disease (in English and Spanish)
More information about the UK Medical Research Council Cognitive Function and Ageing Study (MRC CFAS) is available
PMCID: PMC2765638  PMID: 19901977
2.  Atherosclerosis, Dementia, and Alzheimer’s Disease in the BLSA Cohort 
Annals of neurology  2010;68(2):231-240.
Although it is now accepted that asymptomatic cerebral infarcts are an important cause of dementia in the elderly, the relationship between atherosclerosis per se and dementia is controversial. Specifically, it is unclear whether atherosclerosis can cause the neuritic plaques and neurofibrillary tangles that define Alzheimer neuropathology and whether atherosclerosis, a potentially reversible risk factor, can influence cognition independent of brain infarcts.
We examined the relationship between systemic atherosclerosis, Alzheimer type pathology and dementia in autopsies from 200 participants in the Baltimore Longitudinal Study of Aging (BLSA), a prospective study of the effect of aging on cognition, 175 of whom had complete body autopsies.
Using a quantitative analysis of atherosclerosis in the aorta, heart and intracranial vessels, we found no relationship between the degree of atherosclerosis in any of these systems and the degree of Alzheimer’s type brain pathology. However, we found that the presence of intracranial but not coronary or aortic atherosclerosis significantly increased the odds of dementia, independent of cerebral infarction. Given the large number of individuals with intracranial atherosclerosis in this cohort (136/200), the population attributable risk of dementia related to intracranial atherosclerosis (independent of infarction) is substantial and potentially reversible.
Atherosclerosis of the intracranial arteries is an independent and important risk factor for dementia, suggesting potentially reversible pathways unrelated to Alzheimer’s pathology and stroke through which vascular changes may influence dementia risk.
PMCID: PMC3030772  PMID: 20695015
3.  Age, Alzheimer’s disease and dementia in the Baltimore Longitudinal Study of Ageing 
Brain  2010;133(8):2225-2231.
Recent studies suggest that dementia in the most elderly (90 years of age and above) is only modestly related to Alzheimer’s disease pathology. This raises the possibility that other, as yet unknown, disease processes may underlie dementia in this rapidly growing demographic group, and that efforts designed to combat Alzheimer’s disease may not be appropriate for treating dementia in very elderly subjects. To study this question more closely, we examined the relationship between neocortical Alzheimer-type brain pathology and dementia in consecutive autopsies from 209 participants in the Baltimore Longitudinal Study of Ageing, a prospective longitudinal cohort study of the effect of ageing on cognition. Almost half of the cohort was older than 90 years of age at death. We found that several measures of neocortical Alzheimer’s pathology, including the Consortium to Establish a Registry of Alzheimer’s Disease neuritic plaque score and the Braak neurofibrillary tangle score, remained significant predictors of dementia, independent of age. In participants older than 90 years of age, intracranial atherosclerosis emerged as an important predictor of dementia in subjects with low Alzheimer’s pathology scores, but did not mitigate the importance or population attributable risk of high Alzheimer’s pathology scores on the odds of dementia. There was evidence that the threshold score for neurofibrillary pathology to cause dementia increased in the oldest subjects, but this was offset by an overall increase in neurofibrillary pathology in this age group. We conclude that neocortical Alzheimer’s disease pathology remains significantly correlated with dementia, independent of age. In the most elderly, atherosclerosis also emerged as a cause of dementia in subjects with low Alzheimer’s pathology scores. We found no evidence for a significant number of elderly subjects having dementia without an apparent cause.
PMCID: PMC3139933  PMID: 20647264
Alzheimer’s disease; pathology; ageing; natural history; neurodegenerative mechanisms
4.  Flavanols, Mild Cognitive Impairment, and Alzheimer's Dementia 
Alzheimer's disease (AD) is a dementing neurological disorder that results in progressive memory loss and cognitive decline thought to be associated with buildup of amyloid plaques and neurofibrillary tangles in the brain. Vascular Dementia (VaD) is another common dementing disorder characterized by decreased brain perfusion. Together, AD and VaD constitute mixed dementia, an extremely common type of dementia associated with aging. Neuroimaging research suggests that brain vascular atrophy results in mild cognitive impairment (MCI), a possible precursor for AD. Additionally, literature suggests that attention to cardiovascular risk factors such as hypertension could reduce or delay the incidence of mixed dementia. Furthermore, foods and beverages rich in natural antioxidant flavanoids (i.e. epicatechin and catechin) are currently being advocated as possible preventative agents for a number of pathological conditions ranging from coronary heart disease to dementia. Experimental evidence is mounting that oxidative stress is involved in the pathophysiology of AD, and numerous studies are indicating that polyphenolic antioxidants found in fruits and vegetables can be useful in countering this and blocking neuronal death. More specifically, several cocoa studies suggest that daily intake of cocoa flavanols leads to cardiovascular benefits including vasodilatation via a nitric oxide mechanism and increased brain perfusion. The following text will consider an important question that thus arises regarding the potential of flavanols as effective agents for the prevention and delay of the onset of brain vascular atrophy and subsequently MCI and AD. It will also review the molecular mechanisms through which flavanols operate to accomplish their protective effects.
PMCID: PMC2596318  PMID: 19079672
Brain vascular atrophy; mild cognitive impairment; Alzheimer's disease; flavanols; oxidative stress; antioxidants
5.  Midlife blood pressure, plasma β amyloid and the risk for Alzheimer’s disease: the Honolulu Asia Aging Study 
Hypertension  2012;59(4):780-786.
Beta-amyloid (Aβ), a vasoactive protein, and elevated blood pressure (BP) levels are associated with Alzheimer’s disease (AD) and possibly vascular dementia (VaD). We investigated the joint association of mid-life BP and Aβ peptide levels with the risk for late-life AD and VaD. Subjects were 667 Japanese-American men (including 73 with a brain autopsy), from the prospective Honolulu Heart Program/Honolulu Asia Aging Study (1965 – 2000). Mid-life BP was measured starting in 1971 participants mean age 58 years, Aβ was measured in specimens collected1980/82, and assessment of dementia and autopsy collection started in 1991/93. The outcome measures were prevalent (present in 1991/3) and incident AD (n= 53, including 38 with no contributing cardiovascular disease), and VaD (n=24). Cerebral amyloid angiopathy (CAA), β-amyloid neuritic plaques, and neurofibrillary tangles were evaluated in post-mortem tissue. The risk for AD significantly increased with lower levels of plasma Aβ (Aβ1-40 hazard ratio (HR) 2.1, 95% confidence interval (CI) 1.4 – 3.1; Aβ1-42 HR 1.6, 95% CI 1.1 – 2.3). Evidence of interaction between diastolic BP and plasma Aβ (1-40 pinteraction <0.05; 1-42 pinteraction <0.07) levels, indicated the Aβ-related risk for AD was higher when BP was higher. Low plasma Aβ was associated with the presence of CAA (ptrend<0.05), but not the other neuropathologies. Aβ plasma levels start decreasing at least 15 years before AD is diagnosed, and the association of Aβ to AD is modulated by mid-life diastolic BP. Elevated BP may compromise vascular integrity leading to CAA and impaired Aβ clearance from the brain.
PMCID: PMC3319436  PMID: 22392902
Amyloid; blood pressure; brain; aging; dementia
6.  Nonsteroidal anti-inflammatory drugs are associated with increased neuritic plaques(e–Pub ahead of print) 
Neurology  2010;75(13):1203-1210.
Observational and experimental studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) may protect against Alzheimer disease (AD); however, clinical trials and other observational studies, including the Adult Changes in Thought (ACT) study, show no protection or promotion of AD. The objective of this study is to determine the relationship between common dementia-associated pathologies and mid- to late-life NSAID exposure.
We examined the association of mid- to late-life NSAID use with neuropathologic findings on 257 autopsies from ACT, a population-based study of brain aging and incident dementia. Cumulative standard daily doses (SDD) of nonselective NSAIDs were determined from ≥10 years of computerized pharmacy dispensing data. Analyses were adjusted for selection bias to broaden generalizability of results to 3,026 eligible participants in the ACT cohort. Seven pathologic indices were evaluated: intermediate or frequent score for neuritic plaques, Braak stages V or VI for neurofibrillary tangles, >2 cerebral microinfarcts, the presence of any neocortical Lewy bodies, any macroscopic infarcts, any amyloid angiopathy, and moderate or severe atherosclerosis.
Of the neuropathologic indices evaluated, only neuritic plaque score was significantly increased in participants with greater use of nonselective NSAIDs (p = 0.065), specifically in those with high levels of cumulative use: 1,000–2,000 SDD (adjusted relative risk [RR] 2.16, 95% confidence interval [CI] 1.02–4.25, compared to light/nonuse [<60 SDD]) and >2,000 SDD (adjusted RR 2.37, 95% CI 1.24–4.67).
Increased neuritic plaque accumulation may explain the association between heavy use of nonselective NSAIDs and increased risk of dementia among ACT participants.
= amyloid angiopathy;
= Adult Changes in Thought;
= Alzheimer disease;
= Consortium to Establish a Registry for Alzheimer's Disease;
= confidence interval;
= cerebral microinfarct;
= Diagnostic and Statistical Manual of Mental Disorders, 4th edition;
= Group Health Cooperative;
= Lewy body disease;
= neurofibrillary tangle;
= neuritic plaque;
= nonsteroidal anti-inflammatory drug;
= over-the-counter;
= relative risk;
= standard daily dose;
= vascular brain injury.
PMCID: PMC3013492  PMID: 20811000
7.  Vascular Contributions to Cognitive Impairment and Dementia 
Background and Purpose
This scientific statement provides an overview of the evidence on vascular contributions to cognitive impairment and dementia. Vascular contributions to cognitive impairment and dementia of later life are common. Definitions of vascular cognitive impairment (VCI), neuropathology, basic science and pathophysiological aspects, role of neuroimaging and vascular and other associated risk factors, and potential opportunities for prevention and treatment are reviewed. This statement serves as an overall guide for practitioners to gain a better understanding of VCI and dementia, prevention, and treatment.
Writing group members were nominated by the writing group co-chairs on the basis of their previous work in relevant topic areas and were approved by the American Heart Association Stroke Council Scientific Statement Oversight Committee, the Council on Epidemiology and Prevention, and the Manuscript Oversight Committee. The writing group used systematic literature reviews (primarily covering publications from 1990 to May 1, 2010), previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and, when appropriate, formulate recommendations using standard American Heart Association criteria. All members of the writing group had the opportunity to comment on the recommendations and approved the final version of this document. After peer review by the American Heart Association, as well as review by the Stroke Council leadership, Council on Epidemiology and Prevention Council, and Scientific Statements Oversight Committee, the statement was approved by the American Heart Association Science Advisory and Coordinating Committee.
The construct of VCI has been introduced to capture the entire spectrum of cognitive disorders associated with all forms of cerebral vascular brain injury—not solely stroke—ranging from mild cognitive impairment through fully developed dementia. Dysfunction of the neurovascular unit and mechanisms regulating cerebral blood flow are likely to be important components of the pathophysiological processes underlying VCI. Cerebral amyloid angiopathy is emerging as an important marker of risk for Alzheimer disease, microinfarction, microhemorrhage and macrohemorrhage of the brain, and VCI. The neuropathology of cognitive impairment in later life is often a mixture of Alzheimer disease and microvascular brain damage, which may overlap and synergize to heighten the risk of cognitive impairment. In this regard, magnetic resonance imaging and other neuroimaging techniques play an important role in the definition and detection of VCI and provide evidence that subcortical forms of VCI with white matter hyperintensities and small deep infarcts are common. In many cases, risk markers for VCI are the same as traditional risk factors for stroke. These risks may include but are not limited to atrial fibrillation, hypertension, diabetes mellitus, and hypercholesterolemia. Furthermore, these same vascular risk factors may be risk markers for Alzheimer disease. Carotid intimal-medial thickness and arterial stiffness are emerging as markers of arterial aging and may serve as risk markers for VCI. Currently, no specific treatments for VCI have been approved by the US Food and Drug Administration. However, detection and control of the traditional risk factors for stroke and cardiovascular disease may be effective in the prevention of VCI, even in older people.
Vascular contributions to cognitive impairment and dementia are important. Understanding of VCI has evolved substantially in recent years, based on preclinical, neuropathologic, neuroimaging, physiological, and epidemiological studies. Transdisciplinary, translational, and transactional approaches are recommended to further our understanding of this entity and to better characterize its neuropsychological profile. There is a need for prospective, quantitative, clinical-pathological-neuroimaging studies to improve knowledge of the pathological basis of neuroimaging change and the complex interplay between vascular and Alzheimer disease pathologies in the evolution of clinical VCI and Alzheimer disease. Long-term vascular risk marker interventional studies beginning as early as midlife may be required to prevent or postpone the onset of VCI and Alzheimer disease. Studies of intensive reduction of vascular risk factors in high-risk groups are another important avenue of research.
PMCID: PMC3778669  PMID: 21778438
AHA Scientific Statements; vascular dementia; Alzheimer disease; risk factors; prevention; treatment
8.  Cortical Neuritic Plaques and Hippocampal Neurofibrillary Tangles are Related to Dementia Severity in Elderly Schizophrenia Patients 
Schizophrenia research  2010;116(1):90-96.
Cognitive decline has been described in elderly patients with schizophrenia, but the underlying pathology remains unknown. Some studies report increases in plaques and neurofibrillary tangles, but there is no evidence for an increased risk for Alzheimer’s disease (AD) in elderly schizophrenics. Models of a decreased cerebral reserve suggest that increases in AD-related neuropathology below the threshold for a neuropathological diagnosis could be related to dementia severity in elderly schizophrenia patients. We tested this hypothesis in 110 autopsy specimens of schizophrenia patients , without a neuropatholgical diagnosis of AD or other neurdegenerative disorders. Furthermore, we assessed the effects of apolipoprotein E (ApoE) status, a known genetic risk factor for AD. Measures of density of neuritic plaques were obtained in five cortical regions, and the degree of hippocampal neurofibrillary tangles was rated. Dementia severity was measured prior to postmortem using the Clinical Dementia Rating (CDR) scale. In multivariate analyses of variance were conducted with the factors dementia severity, by ApoE4 carrier status. Hippocampal neurofibrillary tangles correlated with increased dementia severity (p < .05). Neuritic plaque density increased with greater dementia severity (p < .005), and ApoE4 carrier status (p < .005), and these differences were magnified by ApoE4 carrier status (p < .01). Even below the threshold for a neuropathological diagnosis of AD, neuritic plaques and hippocampal neurofibrillary tangles are associated with dementia severity in schizophrenia patients, even more so in the presence of genetic risk factors, suggesting that a decreased cerebral reserve in elderly schizophrenics may increase susceptibilty for dementia.
PMCID: PMC2795077  PMID: 19896333
Schizophrenia; Alzheimer’s Disease; Neuropathology
9.  Genetic Predisposition to Increased Blood Cholesterol and Triglyceride Lipid Levels and Risk of Alzheimer Disease: A Mendelian Randomization Analysis 
PLoS Medicine  2014;11(9):e1001713.
In this study, Proitsi and colleagues use a Mendelian randomization approach to dissect the causal nature of the association between circulating lipid levels and late onset Alzheimer's Disease (LOAD) and find that genetic predisposition to increased plasma cholesterol and triglyceride lipid levels is not associated with elevated LOAD risk.
Please see later in the article for the Editors' Summary
Although altered lipid metabolism has been extensively implicated in the pathogenesis of Alzheimer disease (AD) through cell biological, epidemiological, and genetic studies, the molecular mechanisms linking cholesterol and AD pathology are still not well understood and contradictory results have been reported. We have used a Mendelian randomization approach to dissect the causal nature of the association between circulating lipid levels and late onset AD (LOAD) and test the hypothesis that genetically raised lipid levels increase the risk of LOAD.
Methods and Findings
We included 3,914 patients with LOAD, 1,675 older individuals without LOAD, and 4,989 individuals from the general population from six genome wide studies drawn from a white population (total n = 10,578). We constructed weighted genotype risk scores (GRSs) for four blood lipid phenotypes (high-density lipoprotein cholesterol [HDL-c], low-density lipoprotein cholesterol [LDL-c], triglycerides, and total cholesterol) using well-established SNPs in 157 loci for blood lipids reported by Willer and colleagues (2013). Both full GRSs using all SNPs associated with each trait at p<5×10−8 and trait specific scores using SNPs associated exclusively with each trait at p<5×10−8 were developed. We used logistic regression to investigate whether the GRSs were associated with LOAD in each study and results were combined together by meta-analysis. We found no association between any of the full GRSs and LOAD (meta-analysis results: odds ratio [OR] = 1.005, 95% CI 0.82–1.24, p = 0.962 per 1 unit increase in HDL-c; OR = 0.901, 95% CI 0.65–1.25, p = 0.530 per 1 unit increase in LDL-c; OR = 1.104, 95% CI 0.89–1.37, p = 0.362 per 1 unit increase in triglycerides; and OR = 0.954, 95% CI 0.76–1.21, p = 0.688 per 1 unit increase in total cholesterol). Results for the trait specific scores were similar; however, the trait specific scores explained much smaller phenotypic variance.
Genetic predisposition to increased blood cholesterol and triglyceride lipid levels is not associated with elevated LOAD risk. The observed epidemiological associations between abnormal lipid levels and LOAD risk could therefore be attributed to the result of biological pleiotropy or could be secondary to LOAD. Limitations of this study include the small proportion of lipid variance explained by the GRS, biases in case-control ascertainment, and the limitations implicit to Mendelian randomization studies. Future studies should focus on larger LOAD datasets with longitudinal sampled peripheral lipid measures and other markers of lipid metabolism, which have been shown to be altered in LOAD.
Please see later in the article for the Editors' Summary
Editors' Summary
Currently, about 44 million people worldwide have dementia, a group of brain disorders characterized by an irreversible decline in memory, communication, and other “cognitive” functions. Dementia mainly affects older people and, because people are living longer, experts estimate that more than 135 million people will have dementia by 2050. The commonest form of dementia is Alzheimer disease. In this type of dementia, protein clumps called plaques and neurofibrillary tangles form in the brain and cause its degeneration. The earliest sign of Alzheimer disease is usually increasing forgetfulness. As the disease progresses, affected individuals gradually lose their ability to deal with normal daily activities such as dressing. They may become anxious or aggressive or begin to wander. They may also eventually lose control of their bladder and of other physical functions. At present, there is no cure for Alzheimer disease although some of its symptoms can be managed with drugs. Most people with the disease are initially cared for at home by relatives and other unpaid carers, but many patients end their days in a care home or specialist nursing home.
Why Was This Study Done?
Several lines of evidence suggest that lipid metabolism (how the body handles cholesterol and other fats) is altered in patients whose Alzheimer disease develops after the age of 60 years (late onset Alzheimer disease, LOAD). In particular, epidemiological studies (observational investigations that examine the patterns and causes of disease in populations) have found an association between high amounts of cholesterol in the blood in midlife and the risk of LOAD. However, observational studies cannot prove that abnormal lipid metabolism (dyslipidemia) causes LOAD. People with dyslipidemia may share other characteristics that cause both dyslipidemia and LOAD (confounding) or LOAD might actually cause dyslipidemia (reverse causation). Here, the researchers use “Mendelian randomization” to examine whether lifetime changes in lipid metabolism caused by genes have a causal impact on LOAD risk. In Mendelian randomization, causality is inferred from associations between genetic variants that mimic the effect of a modifiable risk factor and the outcome of interest. Because gene variants are inherited randomly, they are not prone to confounding and are free from reverse causation. So, if dyslipidemia causes LOAD, genetic variants that affect lipid metabolism should be associated with an altered risk of LOAD.
What Did the Researchers Do and Find?
The researchers investigated whether genetic predisposition to raised lipid levels increased the risk of LOAD in 10,578 participants (3,914 patients with LOAD, 1,675 elderly people without LOAD, and 4,989 population controls) using data collected in six genome wide studies looking for gene variants associated with Alzheimer disease. The researchers constructed a genotype risk score (GRS) for each participant using genetic risk markers for four types of blood lipids on the basis of the presence of single nucleotide polymorphisms (SNPs, a type of gene variant) in their DNA. When the researchers used statistical methods to investigate the association between the GRS and LOAD among all the study participants, they found no association between the GRS and LOAD.
What Do These Findings Mean?
These findings suggest that the genetic predisposition to raised blood levels of four types of lipid is not causally associated with LOAD risk. The accuracy of this finding may be affected by several limitations of this study, including the small proportion of lipid variance explained by the GRS and the validity of several assumptions that underlie all Mendelian randomization studies. Moreover, because all the participants in this study were white, these findings may not apply to people of other ethnic backgrounds. Given their findings, the researchers suggest that the observed epidemiological associations between abnormal lipid levels in the blood and variation in lipid levels for reasons other than genetics, or to LOAD risk could be secondary to variation in lipid levels for reasons other than genetics, or to LOAD, a possibility that can be investigated by studying blood lipid levels and other markers of lipid metabolism over time in large groups of patients with LOAD. Importantly, however, these findings provide new information about the role of lipids in LOAD development that may eventually lead to new therapeutic and public-health interventions for Alzheimer disease.
Additional Information
Please access these websites via the online version of this summary at
The UK National Health Service Choices website provides information (including personal stories) about Alzheimer's disease
The UK not-for-profit organization Alzheimer's Society provides information for patients and carers about dementia, including personal experiences of living with Alzheimer's disease
The US not-for-profit organization Alzheimer's Association also provides information for patients and carers about dementia and personal stories about dementia
Alzheimer's Disease International is the international federation of Alzheimer disease associations around the world; it provides links to individual associations, information about dementia, and links to World Alzheimer Reports
MedlinePlus provides links to additional resources about Alzheimer's disease (in English and Spanish)
Wikipedia has a page on Mendelian randomization (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
PMCID: PMC4165594  PMID: 25226301
10.  The apolipoprotein E allele epsilon 4 does not correlate with the number of senile plaques or neurofibrillary tangles in patients with Alzheimer's disease. 
BACKGROUND AND OBJECTIVES: Apolipoprotein E (apoE) has been implicated in regenerative processes in the brain after trauma, as well as in the pathogenesis of Alzheimer's disease. Inheritance of a specific apo epsilon allele (apo epsilon 4) determines in part the risk and the mean age at onset of Alzheimer's disease. ApoE has been found to bind isoform specifically to beta-amyloid protein, the major component of senile plaques, and to the microtubule associated protein tau, which forms paired helical filaments and neurofibrillary tangles. The aim was to further examine the relation between apo epsilon alleles, especially apo epsilon 4, and the development of neuropathological changes associated with Alzheimer's disease. METHODS: Brains of patients with Alzheimer's disease (n = 44) and vascular dementia (n = 11) and of age matched controls (n = 29) were studied. Senile plaques and neurofibrillary tangles in the hippocampus and frontal cortex were quantified. RESULTS: No correlation was found between the number of apo epsilon 4 alleles and the number of senile plaques and neurofibrillary tangles in the hippocampus or the frontal cortex of patients with Alzheimer's disease, or vascular dementia, or control groups. No significant differences in duration or severity of dementia were found between patients with or. without the apo epsilon 4 allele. No increased frequency of apo epsilon 4 was found in vascular dementia. CONCLUSION AND COMMENT: Although the apo epsilon genotype clearly affects whether Alzheimer's disease will develop or not, the present study suggests that it has no influence on pathology or clinical intellectual status, once the dementia has manifested itself. No increased apo epsilon 4 allele frequency was found in neuropathologically diagnosed patients with vascular dementia in whom concomitant Alzheimer's disease can be excluded.
PMCID: PMC486574  PMID: 8890772
11.  Genetic Polymorphisms of a Novel Vascular Susceptibility Gene, Ninjurin2 (NINJ2), Are Associated with a Decreased Risk of Alzheimer's Disease 
PLoS ONE  2011;6(6):e20573.
Accumulated evidences have shown that vascular risk factors, e.g., hypertension, diabetes mellitus and hyperlipidemia, may be related to the risk of dementia. This study investigated the association between genetic polymorphisms of a vascular susceptibility gene, Ninjurin2 (NINJ2), and the risk of dementia, which has not been explored previously.
A total of 275 Alzheimer's disease (AD) patients and 119 vascular dementia (VaD) patients aged 50 or older were recruited from three teaching hospitals from 2007 to 2010. Healthy controls (n = 423) with the same age of cases were recruited from the health checkup and volunteers worked at the hospital during the same time period. Five common (frequency >5%) haplotype-tagging single nucleotide polymorphisms (htSNPs) in NINJ2 were genotyped to test for the association between sequence variants of NINJ2 and dementia risk, and how vascular risk factors modify this association.
Homozygosity of two NINJ2 SNPs was significantly associated with a decreased risk of AD [rs11833579: adjusted odds ratio (AOR) = 0.43; 95% confidence interval (CI)  = 0.23–0.80; rs12425791: AOR  = 0.33, 95% CI  = 0.12–0.96]. Five common haplotypes (cumulative frequency  = 97%) were identified. The global test for the association between NINJ2 haplotypes and AD was significant (p = 0.03). Haplotype CAGGA was significantly associated with a decreased risk of AD (AOR  = 0.32, 95% CI  = 0.11–0.94). No associations were observed for VaD.
Inherited polymorphisms of the vascular susceptibility gene NINJ2 were associated with AD risk.
PMCID: PMC3108950  PMID: 21674003
12.  Carotid Atherosclerosis and Prospective Risk of Dementia 
Background and Purpose
Though vascular risk factors have been implicated in the development of all-cause dementia and Alzheimer’s disease (AD), few studies have examined the association between subclinical atherosclerosis and prospective risk of dementia.
Participants from the Baltimore Longitudinal Study of Aging (n=364, aged 60–95, median age=73, 60% male, 82% white) underwent initial carotid atherosclerosis assessment and were subsequently assessed for dementia and AD annually for up to 14 years (median=7.0). Cox proportional hazards models predicting (a) all-cause dementia and (b) AD were adjusted for age, sex, race, education, blood pressure, cholesterol, cardiovascular disease, diabetes, and smoking.
Sixty participants developed dementia, with 53 diagnosed as Alzheimer’s disease. Raw rates of future dementia and AD among individuals initially (a) in the upper quintile of carotid intimal medial thickness (IMT) or (b) with bilateral carotid plaque were generally double the rates of individuals with IMT in the lower quintiles or no plaque at baseline. Adjusted proportional hazards models revealed a >2.5-fold increased risk of dementia and AD among individuals in the upper quintile of carotid IMT, and a nearly 2.0-fold increased risk of dementia among individuals with bilateral plaque.
Multiple measures of carotid atherosclerosis are associated with prospective risk of dementia. Individuals in the upper quintile of carotid IMT or bilateral carotid plaque were at greatest risk. These findings underscore the possibility that early intervention to reduce atherosclerosis may help delay or prevent onset of dementia and AD.
PMCID: PMC3508298  PMID: 23103489
atherosclerosis; intimal medial thickness; dementia; Alzheimer’s disease
13.  Plasma homocysteine, Alzheimer and cerebrovascular pathology: a population-based autopsy study 
Brain  2013;136(9):2707-2716.
Elevated plasma total homocysteine is associated with increased risk of dementia/Alzheimer’s disease, but underlying pathophysiological mechanisms are not fully understood. This study investigated possible links between baseline homocysteine, and post-mortem neuropathological and magnetic resonance imaging findings up to 10 years later in the Vantaa 85+ population including people aged ≥85 years. Two hundred and sixty-five individuals had homocysteine and autopsy data, of which 103 had post-mortem brain magnetic resonance imaging scans. Methenamine silver staining was used for amyloid-β and modified Bielschowsky method for neurofibrillary tangles and neuritic plaques. Macroscopic infarcts were identified from cerebral hemispheres, brainstem and cerebellum slices. Standardized methods were used to determine microscopic infarcts, cerebral amyoloid angiopathy, and α-synuclein pathology. Magnetic resonance imaging was used for visual ratings of the degree of medial temporal lobe atrophy, and periventricular and deep white matter hyperintensities. Elevated baseline homocysteine was associated with increased neurofibrillary tangles count at the time of death: for the highest homocysteine quartile, odds ratio (95% confidence interval) was 2.60 (1.28–5.28). The association was observed particularly in people with dementia, in the presence of cerebral infarcts, and with longer time between the baseline homocysteine assessment and death. Also, elevated homocysteine tended to relate to amyloid-β accumulation, but this was seen only with longer baseline-death interval: odds ratio (95% confidence interval) was 2.52 (0.88–7.19) for the highest homocysteine quartile. On post-mortem magnetic resonance imaging, for the highest homocysteine quartile odds ratio (95% confidence interval) was 3.78 (1.12–12.79) for more severe medial temporal atrophy and 4.69 (1.14–19.33) for more severe periventricular white matter hyperintensities. All associations were independent of several potential confounders, including common vascular risk factors. No relationships between homocysteine and cerebral macro- or microinfarcts, cerebral amyoloid angiopathy or α-synuclein pathology were detected. These results suggest that elevated homocysteine in adults aged ≥85 years may contribute to increased Alzheimer-type pathology, particularly neurofibrillary tangles burden. This effect seems to be more pronounced in the presence of cerebrovascular pathology. Randomized controlled trials are needed to determine the impact of homocysteine-lowering treatments on dementia-related pathology.
PMCID: PMC3754457  PMID: 23983028
homocysteine; Alzheimer’s disease; Alzheimer pathology; cerebrovascular pathology; elderly
14.  Genome-Wide Association Meta-analysis of Neuropathologic Features of Alzheimer's Disease and Related Dementias 
PLoS Genetics  2014;10(9):e1004606.
Alzheimer's disease (AD) and related dementias are a major public health challenge and present a therapeutic imperative for which we need additional insight into molecular pathogenesis. We performed a genome-wide association study and analysis of known genetic risk loci for AD dementia using neuropathologic data from 4,914 brain autopsies. Neuropathologic data were used to define clinico-pathologic AD dementia or controls, assess core neuropathologic features of AD (neuritic plaques, NPs; neurofibrillary tangles, NFTs), and evaluate commonly co-morbid neuropathologic changes: cerebral amyloid angiopathy (CAA), Lewy body disease (LBD), hippocampal sclerosis of the elderly (HS), and vascular brain injury (VBI). Genome-wide significance was observed for clinico-pathologic AD dementia, NPs, NFTs, CAA, and LBD with a number of variants in and around the apolipoprotein E gene (APOE). GalNAc transferase 7 (GALNT7), ATP-Binding Cassette, Sub-Family G (WHITE), Member 1 (ABCG1), and an intergenic region on chromosome 9 were associated with NP score; and Potassium Large Conductance Calcium-Activated Channel, Subfamily M, Beta Member 2 (KCNMB2) was strongly associated with HS. Twelve of the 21 non-APOE genetic risk loci for clinically-defined AD dementia were confirmed in our clinico-pathologic sample: CR1, BIN1, CLU, MS4A6A, PICALM, ABCA7, CD33, PTK2B, SORL1, MEF2C, ZCWPW1, and CASS4 with 9 of these 12 loci showing larger odds ratio in the clinico-pathologic sample. Correlation of effect sizes for risk of AD dementia with effect size for NFTs or NPs showed positive correlation, while those for risk of VBI showed a moderate negative correlation. The other co-morbid neuropathologic features showed only nominal association with the known AD loci. Our results discovered new genetic associations with specific neuropathologic features and aligned known genetic risk for AD dementia with specific neuropathologic changes in the largest brain autopsy study of AD and related dementias.
Author Summary
Alzheimer's disease (AD) and related dementias are a major public health challenge and present a therapeutic imperative for which we need additional insight into molecular pathogenesis. We performed a genome-wide association study (GWAS), as well as an analysis of known genetic risk loci for AD dementia, using data from 4,914 brain autopsies. Genome-wide significance was observed for 7 genes and pathologic features of AD and related diseases. Twelve of the 22 genetic risk loci for clinically-defined AD dementia were confirmed in our pathologic sample. Correlation of effect sizes for risk of AD dementia with effect size for hallmark pathologic features of AD were strongly positive and linear. Our study discovered new genetic associations with specific pathologic features and aligned known genetic risk for AD dementia with specific pathologic changes in a large brain autopsy study of AD and related dementias.
PMCID: PMC4154667  PMID: 25188341
15.  Is apolipoprotein E4 an important risk factor for vascular dementia? 
Despite the fact that vascular dementia (VaD) represents the seconding leading cause of dementia in the USA, behind only Alzheimer’s disease (AD), there remains a lack of consensus on the pathological criteria required for diagnosis of this disease. A number of clinical diagnostic criteria exist but are poorly validated and inconsistently applied. It is clear that vascular risk factors play an important role in the etiology of VaD, including hypertension, stroke, diabetes, and atherosclerosis. Vascular risk factors may increase the risk for VaD by promoting inflammation, cerebral vascular disease, white matter lesions, and hippocampal sclerosis. Because vascular risk factors seem to impart a high degree of risk for conferring VaD, it seems logical that the apolipoprotein E (APOE) status of individuals may be important. APOE plays a critical role in transporting cholesterol in and out of the CNS and in AD it is known that harboring the APOE allele increases the risk of AD perhaps due to the improper functioning of this protein. The purpose of this review is to examine the important pathological features and risk factors for VaD and to provide a critical assessment of the current literature regarding whether or not apoE4 also confers disease risk in VaD. The preponderance of data suggests that harboring one or both APOE4 alleles elevates the risk for VaD, but not to the same extent as found in AD.
PMCID: PMC4128964  PMID: 25120729
Apolipoprotein E4 (APOE4); vascular dementia; pathology; risk factors; Alzheimer’s disease; neurofibrillary tangles; blood brain barrier; inflammation
16.  Cerebrovascular atherosclerosis correlates with Alzheimer pathology in neurodegenerative dementias 
Brain  2012;135(12):3749-3756.
A growing body of evidence demonstrates an association between vascular risk factors and Alzheimer’s disease. This study investigated the frequency and severity of atherosclerotic plaques in the circle of Willis in Alzheimer’s disease and multiple other neurodegenerative diseases. Semi-quantitative data from gross and microscopic neuropathological examinations in 1000 cases were analysed, including 410 with a primary diagnosis of Alzheimer’s disease, 230 with synucleinopathies, 157 with TDP-43 proteinopathies, 144 with tauopathies and 59 with normal ageing. More than 77% of subjects with Alzheimer’s disease had grossly apparent circle of Willis atherosclerosis, a percentage that was significantly higher than normal (47%), or other neurodegenerative diseases (43–67%). Age- and sex-adjusted atherosclerosis ratings were highly correlated with neuritic plaque, paired helical filaments tau neurofibrillary tangle and cerebral amyloid angiopathy ratings in the whole sample and within individual groups. We found no associations between atherosclerosis ratings and α-synuclein or TDP-43 lesion ratings. The association between age-adjusted circle of Willis atherosclerosis and Alzheimer’s disease–type pathology was more robust for female subjects than male subjects. These results provide further confirmation and specificity that vascular disease and Alzheimer’s disease are interrelated and suggest that common aetiologic or reciprocally synergistic pathophysiological mechanisms promote both vascular pathology and plaque and tangle pathology.
PMCID: PMC3577102  PMID: 23204143
atherosclerosis; neuritic plaques; neurofibrillary tangles; synuclein; TDP-43
17.  Epidemiological Aspects of Atherosclerosis in Patients Treated for Acute Atherothrombosis of Extremity Arteries 
Medical Archives  2014;68(5):329-331.
Risk factors for development of extremity artery atherosclerosis are the same as for coronary and cerebrovascular atherosclerosis namely, diabetes mellitus, hyperlipidemia, arterial hypertension, age and smoking. Atherosclerosis is polyarterial disease that clinically manifests itself most frequently in the form coronary, cerebrovascular or peripheral arterial disease (PAD). All of them have common, ominous and final pathologic step – atherosclerotic plaque rupture that might eventually lead to atherothrombosis and signs of ischemia. There are few studies of risk factor for peripheral artery disease (PAD). Aim of study: To identify prevalence of known risk factors for atherosclerosis in patients treated for acute atherothrombosis of extremity arteries.
Patients and methods:
Eighty patient were analyzed with regard to the prevalence of five risk factors for atherosclerosis (diabetes mellitus, smoking, hypertension, hyperlipidemia and age). 80 patients were divided into two groups (Group A and B) depending on country i.e. hospital where they received treatment for acute atherothrombosis of extremity artery. Group A consisted of patients treated at Clinic for vascular surgery in Sarajevo, while patients in Group B were treated in Trollhattan in Sweden at NAL hospital. This study was clinical, comparative, retrospective-prospective.
In group A, 20% of patients had diabetes mellitus while in group B prevalence of diabetics was lower (12,5%) but difference was not statistically significant p>0.05. Sixty percent of patients (60%) in group A were smokers. In Sweden, habit of smoking is not as common as in Balkan countries and consequently only 22,5% of patients were smokers in Group l, difference was statistically significant, p<0.05. In patients assigned to group A, 42.5% of them had diagnosis of hypertension while in Group B, 35% of patients were hypertensive. Difference was not statistically significant, p>0.05. 37.5% of patients in group A and 20% of patients in group B had hyperlipidemia. Difference was not statistically significant, p>0.05. In Group A mean age of patients was 67.85 years while mean age in Group B was 73.63. Age difference was statistically significant, p<0.05.
Prevalence of risk factors of atherosclerosis in peripheral artery disease were evaluated in this study. Significant difference in prevalence of two risk factors were determined namely, smoking and mean age of occurrence of atherothrombosis. Quiting smoking and adopting healthier life habits may lead to reduction of prevalence PAD in younger patients in Bosnia and Herzegovina.
PMCID: PMC4269536  PMID: 25568565
extremity arteries; atherosclerosis; acute atherothrombosis
18.  Risk factors for dementia in the epidemiological study of Munguialde County (Basque Country-Spain) 
BMC Neurology  2008;8:39.
Prevalence of degenerative dementias and dementias associated with cerebrovascular disease is increasing. Dementia is one of the most significant public health problem. In recent years, the role of vascular risk factors (hypertension, diabetes mellitus and hypercholesterolemia) and depression has been evaluated.
The incidence of dementia and risk factors has not been fully investigated in Spain. The aim of this study was to identify the risk factors for dementia, Alzheimer's disease (AD) and vascular dementia (VD) in elderly people in Munguialde County (Spain).
A two phase, door-to-door populational study was performed. Demographic variables and the presence of vascular risk factors and depression were recorded. The MMSE, the DSM-IV and the conventional criteria for AD and VD were used in the evaluation. The odds ratio for each risk factor was calculated by logistic regression analysis.
1756 healthy subjects and 175 patients with dementia participated in the study. Of these, 133 had AD, 15 VD and the remainder other dementias. The risk factors for dementia and AD were female sex (OR = 1.67 and 1.97, respectively); age (OR = 1.14 and 1.15); stroke (OR = 7.84 and 3); and depression (OR = 53.08 and 3.19). Stroke was the only risk factor for VD (OR = 119).
Greater age, female sex, stroke and depression increase the risk of suffering dementia, AD and VD. The relationship between depression, vascular risk factors and dementia has clear public health implications. Prevention and early treatment of vascular risk factors and depression may have an important impact in lowering the risk of dementia and could modify the natural history of the disease.
PMCID: PMC2584030  PMID: 18922150
19.  Vascular dementia: prevention and treatment 
Clinical Interventions in Aging  2006;1(3):229-235.
Vascular dementia (VaD) is the most common cause of dementia in the elderly, second only to Alzheimer’s disease (AD). Between 1% and 4% of people of 65 years of age suffer from VaD and the prevalence appears to double every 5–10 years after the age of 65.
Prevention aims to reduce the disease by eliminating its cause or main risk factors, particularly hypertension as well as diabetes mellitus, atherosclerosis, coronary artery disease, smoking, lipid abnormalities, and hyperhomocystinemia. Initial studies of several agents for symptomatic treatment were disappointing. However, there is growing evidence for cholinergic involvement in VaD and recent studies with cholinesterase inhibitors have shown improvement in cognitive, global function, and activities of daily living as compared with placebo and have been well tolerated.
VaD is a common condition and its prevalence is likely to increase. As physicians we need to be diligent with regards to recognition of risk factors and vigorous intervention. Promising results have been seen in several clinical trials of cholinesterase inhibitors and no safety of tolerability issues have been noted.
PMCID: PMC2695177  PMID: 18046875
vascular dementia; prevention; treatment
20.  Different Patterns of Cerebral Injury in Dementia with or Without Diabetes 
Archives of neurology  2009;66(3):315-322.
Diabetes mellitus (DM) increases the risk of dementia in the elderly. However the underlying mechanisms, its connection with Alzheimer's disease (AD) and vascular cognitive impairment (VCI), and effects of therapy remain unclear.
To test the hypothesis that DM promotes specific neuropathologic processes that contribute to dementia and that these processes may be suppressed by antidiabetic therapy.
A comprehensive neuropathologic assessment of all cases from a community-based study of incident dementia (Adult Changes in Thought study) that underwent autopsies (n=259) and had information on DM status (n=196). Biochemical analysis was conducted on a subset of these cases with rapidly frozen brain tissue (n=57).
Autopsy cases were divided into four groups: no DM/no dementia (DM−/dementia−), DM/no dementia (DM+/dementia−), no DM/dementia (DM−/dementia+), and DM/dementia (DM+/ dementia+). Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) diagnosis of dementia was assigned through a consensus of experts following biennial cognitive and physical evaluations. Diabetes was diagnosed based on information obtained from participants’ extensive medical records.
In cases without dementia (n=125), neuropathologic or biochemical endpoints did not differ significantly by DM status. However, we observed 2 patterns of injury in patients with dementia (n=71) by their DM status. Individuals without DM, but with dementia (DM−/dementia+) had greater Aβ peptide load and increased F2-isoprostanes in the cerebral cortex, while DM+/dementia+ patients had more microvascular infarcts (MVI) and an increased cortical IL-6 (interleukin 6) concentration. The number of microvascular infarcts was greater in deep cerebral structures in patients with dementia whose diabetes was treated, whereas amyloid plaque load tended to be greater for untreated diabetic patients with dementia.
These novel characterizations of 2 different patterns of cerebral injury in patients with dementia depending on DM status may have etiologic and therapeutic implications.
PMCID: PMC2766529  PMID: 19139294
21.  Examination of the Clinicopathologic Continuum of Alzheimer Disease in the Autopsy Cohort of the National Alzheimer Coordinating Center 
To test the hypothesis that Alzheimer disease (AD) is a clinical and pathologic continuum between normal aging and end-stage dementia, we selected a convenience sample of subjects from the National Alzheimer Coordinating Center 2005 to 2012 autopsy cohort (n = 2,083) with the last clinical evaluation within 2 years before autopsy and no other primary neuropathologic diagnosis. Demographic and neuropathologic characteristics were correlated with the Clinical Dementia Rating–Sum of Boxes in the 835 subjects meeting these criteria. Both neuritic plaques and neurofibrillary tangles independently predicted Clinical Dementia Rating–Sum of Boxes. Severe small-vessel disease, severe amyloid angiopathy, and hippocampal sclerosis were also independently associated with the degree of cognitive impairment. By contrast, education was a strong independent protective factor against cognitive deficits. The cause of mild to moderate dementia remained uncertain in 14% of the patients. Inverse probability weighting suggests the generalizability of these results to nonautopsied cohorts. These data indicate that plaques and tangles independently contribute to cognitive impairment, that concurrent vascular disease strongly correlates with cognitive dysfunction even in a sample selected to represent the AD pathologic continuum, and that education further modifies clinical expression. Thus, multiple concomitant etiologies of brain damage and premorbid characteristics contribute to the uncertainty of AD clinicopathologic correlations based only on tangles and plaques.
PMCID: PMC3962953  PMID: 24226270
Alzheimer disease; Cerebral amyloid angiopathy; Hippocampal sclerosis; Neuritic plaques; Neurofibrillary tangles; Small-vessel disease
22.  Cancer linked to Alzheimer disease but not vascular dementia 
Neurology  2010;74(2):106-112.
To investigate whether cancer is associated with Alzheimer disease (AD) and vascular dementia (VaD).
Cox proportional hazards models were used to test associations between prevalent dementia and risk of future cancer hospitalization, and associations between prevalent cancer and risk of subsequent dementia. Participants in the Cardiovascular Health Study–Cognition Substudy, a prospective cohort study, aged 65 years or older (n = 3,020) were followed a mean of 5.4 years for dementia and 8.3 years for cancer.
The presence of any AD (pure AD + mixed AD/VaD; hazard ratio [HR] = 0.41, 95% confidence interval [CI] = 0.20–0.84) and pure AD (HR = 0.31, 95% CI = 0.12–0.86) was associated with a reduced risk of future cancer hospitalization, adjusted for demographic factors, smoking, obesity, and physical activity. No significant associations were found between dementia at baseline and rate of cancer hospitalizations for participants with diagnoses of VaD. Prevalent cancer was associated with reduced risk of any AD (HR = 0.72; 95% CI = 0.52–0.997) and pure AD (HR = 0.57; 95% CI = 0.36–0.90) among white subjects after adjustment for demographics, number of APOE ε4 alleles, hypertension, diabetes, and coronary heart disease; the opposite association was found among minorities, but the sample size was too small to provide stable estimates. No significant association was found between cancer and subsequent development of VaD.
In white older adults, prevalent Alzheimer disease (AD) was longitudinally associated with a reduced risk of cancer, and a history of cancer was associated with a reduced risk of AD. Together with other work showing associations between cancer and Parkinson disease, these findings suggest the possibility that cancer is linked to neurodegeneration.
= modified Mini-Mental State Examination;
= Alzheimer disease;
= Alzheimer Disease Diagnostic and Treatment Centers;
= coronary heart disease;
= Cardiovascular Health Study;
= confidence interval;
= hazard ratio;
= International Classification of Diseases–Ninth Revision;
= mild cognitive impairment;
= National Institute of Neurological and Communicative Diseases and Stroke–Alzheimer's Disease and Related Disorders Association;
= Parkinson disease;
= vascular dementia.
PMCID: PMC2809029  PMID: 20032288
23.  The occult aftermath of boxing. 
The repeated head trauma experienced by boxers can lead to the development of dementia pugilistica (DP)--punch drunk syndrome. The neuropathology of DP in a classic report by Corsellis et al describes the presence of numerous neurofibrillary tangles in the absence of plaques, in contrast to the profusion of tangles and plaques seen in Alzheimer's disease (AD). The DP cases used in that report were re-investigated with immunocytochemical methods and an antibody raised to the beta-protein present in AD plaques. We found that all DP cases with substantial tangle formation showed evidence of extensive beta-protein immunoreactive deposits (plaques). These diffuse "plaques" were not visible with Congo-red or standard silver stains. The degree of beta-protein deposition was comparable to that seen in AD. Our data indicate that the present neuropathological description of DP (tangles but no plaques) should be altered to acknowledge the presence of substantial beta-protein deposition (plaques). The molecular markers present in the plaques and tangles of DP are the same as those in AD. Similarities in clinical symptoms, distribution of pathology and neurochemical deficits also exist. Epidemiological studies have shown that head injury is a risk factor in AD. It is probable that DP and AD share common pathogenic mechanisms leading to tangle and plaque formation.
PMCID: PMC488051  PMID: 2191084
24.  A Population-Based Clinicopathological Study in the Oldest-Old: The 90+ Study 
Current Alzheimer research  2012;9(6):709-717.
Population-based longitudinal clinicopathological studies provide an ideal opportunity to study a variety of risk and protective factors in relation to pathology associated with dementia in individuals who are representative of the general population. The 90+ Study is a population-based study designed specifically to study aging and dementia as well as its neuropathological correlates in participants 90 years of age and older. We present demographic and pathological data on the first 104 participants to come to autopsy from the brain donation component of the study, The 90+ Autopsy Study. Cognitive diagnosis was assigned according to Diagnostic and Statistical Manual 4th edition criteria for dementia and neuropathological diagnoses were made according to the Consortium to Establish a Registry for Alzheimer’s Disease protocol. Dementia was present in 61% of autopsied participants, the majority of whom were diagnosed with Alzheimer’s disease (85%). Many different types of pathology typically associated with dementia were common in the oldest-old, and included neurofibrillary tangles, neuritic plaques, diffuse plaques, Lewy bodies, hippocampal sclerosis, and cerebral infarctions. Most types of pathology were more frequently found in participants suffering from dementia but there was extensive overlap in pathology among those with and without dementia. In addition, 22% of demented participants did not have sufficient pathology to account for their cognitive loss. Our results highlight the poor associations between these common pathological lesions and dementia in the oldest-old and the importance of considering many different types of pathology, possibly including some yet to be identified, in order to account for all dementias in the oldest-old.
PMCID: PMC3409303  PMID: 22471863
Dementia; Alzheimer’s disease; cohort study; longitudinal studies; neuropathology; oldest-old
25.  Prevalence, Distribution, and Impact of Mild Cognitive Impairment in Latin America, China, and India: A 10/66 Population-Based Study 
PLoS Medicine  2012;9(2):e1001170.
A set of cross-sectional surveys carried out in Cuba, Dominican Republic, Peru, Mexico, Venezuela, Puerto Rico, China, and India reveal the prevalence and between-country variation in mild cognitive impairment at a population level.
Rapid demographic ageing is a growing public health issue in many low- and middle-income countries (LAMICs). Mild cognitive impairment (MCI) is a construct frequently used to define groups of people who may be at risk of developing dementia, crucial for targeting preventative interventions. However, little is known about the prevalence or impact of MCI in LAMIC settings.
Methods and Findings
Data were analysed from cross-sectional surveys established by the 10/66 Dementia Research Group and carried out in Cuba, Dominican Republic, Peru, Mexico, Venezuela, Puerto Rico, China, and India on 15,376 individuals aged 65+ without dementia. Standardised assessments of mental and physical health, and cognitive function were carried out including informant interviews. An algorithm was developed to define Mayo Clinic amnestic MCI (aMCI). Disability (12-item World Health Organization disability assessment schedule [WHODAS]) and informant-reported neuropsychiatric symptoms (neuropsychiatric inventory [NPI-Q]) were measured. After adjustment, aMCI was associated with disability, anxiety, apathy, and irritability (but not depression); between-country heterogeneity in these associations was only significant for disability. The crude prevalence of aMCI ranged from 0.8% in China to 4.3% in India. Country differences changed little (range 0.6%–4.6%) after standardization for age, gender, and education level. In pooled estimates, aMCI was modestly associated with male gender and fewer assets but was not associated with age or education. There was no significant between-country variation in these demographic associations.
An algorithm-derived diagnosis of aMCI showed few sociodemographic associations but was consistently associated with higher disability and neuropsychiatric symptoms in addition to showing substantial variation in prevalence across LAMIC populations. Longitudinal data are needed to confirm findings—in particular, to investigate the predictive validity of aMCI in these settings and risk/protective factors for progression to dementia; however, the large number affected has important implications in these rapidly ageing settings.
Please see later in the article for the Editors' Summary
Editors' Summary
Currently, more than 35 million people worldwide have dementia, a group of brain disorders characterized by an irreversible decline in memory, problem solving, communication, and other “cognitive” functions. Dementia, the commonest form of which is Alzheimer's disease, mainly affects older people and, because more people than ever are living to a ripe old age, experts estimate that, by 2050, more than 115 million people will have dementia. At present, there is no cure for dementia although drugs can be used to manage some of the symptoms. Risk factors for dementia include physical inactivity, infrequent participation in mentally or socially stimulating activities, and common vascular risk factors such as high blood pressure, diabetes, and smoking. In addition, some studies have reported that mild cognitive impairment (MCI) is associated with an increased risk of dementia. MCI can be seen as an intermediate state between normal cognitive aging (becoming increasingly forgetful) and dementia although many people with MCI never develop dementia, and some types of MCI can be static or self-limiting. Individuals with MCI have cognitive problems that are more severe than those normally seen in people of a similar age but they have no other symptoms of dementia and are able to look after themselves. The best studied form of MCI—amnestic MCI (aMCI)—is characterized by memory problems such as misplacing things and forgetting appointments.
Why Was This Study Done?
Much of the expected increase in dementia will occur in low and middle income countries (LAMICs) because these countries have rapidly aging populations. Given that aMCI is frequently used to define groups of people who may be at risk of developing dementia, it would be useful to know what proportion of community-dwelling older adults in LAMICs have aMCI (the prevalence of aMCI). Such information might help governments plan their future health care and social support needs. In this cross-sectional, population-based study, the researchers estimate the prevalence of aMCI in eight LAMICs using data collected by the 10/66 Dementia Research Group. They also investigate the association of aMCI with sociodemographic factors (for example, age, gender, and education), disability, and neuropsychiatric symptoms such as anxiety, apathy, irritability, and depression. A cross-sectional study collects data on a population at a single time point; the 10/66 Dementia Research Group is building an evidence base to inform the development and implementation of policies for improving the health and social welfare of older people in LAMICs, particularly people with dementia.
What Did the Researchers Do and Find?
In cross-sectional surveys carried out in six Latin American LAMICS, China, and India, more than 15,000 elderly individuals without dementia completed standardized assessments of their mental and physical health and their cognitive function. Interviews with relatives and carers provided further details about the participant's cognitive decline and about neuropsychiatric symptoms. The researchers developed an algorithm (set of formulae) that used the data collected in these surveys to diagnose aMCI in the study participants. Finally, they used statistical methods to analyze the prevalence, distribution, and impact of aMCI in the eight LAMICs. The researchers report that aMCI was associated with disability, anxiety, apathy, and irritability but not with depression and that the prevalence of aMCI ranged from 0.8% in China to 4.3% in India. Other analyses show that, considered across all eight countries, aMCI was modestly associated with being male (men had a slightly higher prevalence of aMCI than women) and with having fewer assets but was not associated with age or education.
What Do These Findings Mean?
These findings suggest that aMCI, as diagnosed using the algorithm developed by the researchers, is consistently associated with higher disability and with neuropsychiatric symptoms in the LAMICs studied but not with most sociodemographic factors. Because prevalidated and standardized measurements were applied consistently in all the countries and a common algorithm was used to define aMCI, these findings also suggest that the prevalence of aMCI varies markedly among LAMIC populations and is similar to or slightly lower than the prevalence most often reported for European and North American populations. Although longitudinal studies are now needed to investigate the extent to which aMCI can be used as risk marker for further cognitive decline and dementia in these settings, the large absolute numbers of older people with aMCI in LAMICs revealed here potentially has important implications for health care and social service planning in these rapidly aging and populous regions of the world.
Additional Information
Please access these Web sites via the online version of this summary at
Alzheimer's Disease International is the international federation of Alzheimer associations around the world; it provides links to individual associations, information about dementia, and links to three World Alzheimer Reports; information about the 10/66 Dementia Research Group is also available on this web site
The Alzheimer's Society provides information for patients and carers about dementia, including information on MCI and personal stories about living with dementia
The Alzheimer's Association also provides information for patients and carers about dementia and about MCI, and personal stories about dementia
A BBC radio program that includes an interview with a man with MCI is available
MedlinePlus provides links to further resources about MCI and dementia (in English and Spanish)
PMCID: PMC3274506  PMID: 22346736

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