Amyloid imaging may revolutionize Alzheimer’s disease (AD) research and clinical practice but is critically limited by an inadequate correlation between cerebral cortex amyloid plaques and dementia. Also, amyloid imaging does not indicate the extent of neurofibrillary tangle (NFT) spread throughout the brain. Currently, the presence of dementia as well as a minimal brain load of both plaques and NFTs is required for the diagnosis of AD. Autopsy studies suggest that striatal amyloid plaques may be mainly restricted to subjects in higher Braak NFT stages that meet clinicopathological diagnostic criteria for AD. Striatal plaques, which are readily identified by amyloid imaging, might therefore be used to predict the presence of a higher Braak NFT stage and clinicopathological AD in living subjects. This study determined the sensitivity and specificity of striatal plaques for predicting a higher Braak NFT stage and clinicopathological AD in a postmortem series of 211 elderly subjects. Subjects included 87 clinicopathologically classified as non-demented elderly controls and 124 with AD. A higher striatal plaque density score (moderate or frequent) had 95.8% sensitivity, 75.7% specificity for Braak NFT stage V or VI and 85.6% sensitivity, 86.2% specificity for the presence of dementia and clinicopathological AD (National Institute on Aging – Reagan Institute “intermediate” or “high”). Amyloid imaging of the striatum may be useful as a predictor, in living subjects, of Braak NFT stage and the presence or absence of dementia and clinicopathological AD. Validation of this hypothesis will require autopsy studies of subjects that had amyloid imaging during life.
Alzheimer’s disease; amyloid imaging; striatum; amyloid plaques; diagnosis; therapy; asymptomatic; preclinical; autopsy
Dysphagia is very common in patients with Parkinson’s disease (PD) and often leads to aspiration pneumonia, the most common cause of death in PD. Unfortunately, current therapies are largely ineffective for dysphagia. As pharyngeal sensation normally triggers the swallowing reflex, we examined pharyngeal sensory nerves in PD for Lewy pathology. Sensory nerves supplying the pharynx were excised from autopsied pharynges obtained from patients with clinically diagnosed and neuropathologically confirmed PD (n = 10) and healthy age-matched controls (n = 4). We examined: the glossopharyngeal nerve (IX); the pharyngeal sensory branch of the vagus nerve (PSB-X); and the internal superior laryngeal nerve (ISLN) innervating the laryngopharynx. Immunohistochemistry for phosphorylated α-synuclein was used to detect potential Lewy pathology. Axonal α-synuclein aggregates in the pharyngeal sensory nerves were identified in all of the PD subjects but not in the controls. The density of α-synuclein-positive lesions was significantly greater in PD subjects with documented dysphagia compared to those without dysphagia. In addition, α-synuclein-immunoreactive nerve fibers in the ISLN were much more abundant than those in the IX and PSBX. These findings suggest that pharyngeal sensory nerves are directly affected by the pathologic process of PD. This anatomic pathology may decrease pharyngeal sensation impairing swallowing and airway protective reflexes, thereby contributing to dysphagia and aspiration.
Alpha-synuclein aggregates; Dysphagia; Glossopharyngeal nerve; Immunohistochemistry; Internal superior laryngeal nerve; Lewy neurites; Nerve degeneration; Parkinson disease; Peripheral nervous system; Pharyngeal sensory nerves; Pharynx; Swallowing; Vagus nerve
Carriers of the ApoE ϵ4 allele are at a greater risk for developing Alzheimer’s disease (AD) and those who do develop AD tend to have a much greater neuropathological disease burden. Although several studies have shown significant differences in AD pathology among ϵ4 carriers and non-carriers, few have characterized these differences in terms of brain region and neuropathological score frequency.
566 pathologically-confirmed AD cases who were followed prospectively with antemortem dementia diagnoses (312 ApoE ϵ4 carriers and 254 ApoE ϵ4 non-carriers) were compared on the frequencies of neuropathological frequency scores (none, sparse, moderate, frequent) among several different brain regions (frontal, temporal, parietal, hippocampal, and entorhinal) using the CERAD scoring system. Pathology score frequencies were analyzed by carrier status (ϵ4 carrier vs. ϵ4 non-carrier) and by genotype (2/3, 3/3, 2/4, 3/4, 4/4). Both analyses investigated pathology score frequencies among different brain regions (frontal, temporal, parietal, hippocampal, and entorhinal).
ϵ4 carriers had a significantly lower age at death (p <0.001) and significantly higher Braak scores (p <0.001) than ϵ4 non-carriers. Genotype comparison revealed that plaque and tangle pathologies increased in the following pattern, 2/3<3/3<2/4<3/4<4/4, for several brain regions. When stratified by age and ApoE ϵ4 carrier status, ϵ4 carriers tended to have significantly more frequent scores across most cortical areas. However, non-carriers age 90 and older tended to have greater plaque pathology than carriers. For tangle pathology, ϵ4 carriers tended to have significantly more “frequent” scores than non-carriers, except for the hippocampal and entorhinal areas in individuals age 90 and older.
ApoE ϵ4 carriers had a significantly higher percentage of “frequent” scores for plaques and tangles when compared to ApoE ϵ4 non-carriers for several brain regions. However, ϵ4 non-carriers age 90 and older tended to have less plaque and tangle pathology in certain brain regions. These results demonstrate that AD pathology may manifest itself differently based on ApoE genotype and suggest that ApoE carriers and non-carriers may have different patterns of AD neuropathology location and density.
The pathology of essential tremor is increasingly being studied; however, there are limited studies of biochemical changes in this condition.
We studied several candidate biochemical/anatomical systems in the brainstem, striatum and cerebellum of 23 essential tremor subjects who came to autopsy, comparing them to a control population.
Striatal tyrosine hydroxylase, a marker of dopaminergic neurons, was 91.7 ±113.2 ng/mg versus 96.4±102.7 ng/mg (not significant) in cases and controls. Locus ceruleus dopamine beta-hydroxylase, a marker of noradrenergic neurons, was not significantly different between essential tremor and control groups. Parvalbumin, a marker of GABAergic neurons, was 199.3±42.0 versus 251.4±74.8 ng/mg (p=0.025) in the pons in the region of the locus ceruleus of essential tremor versus controls, while there was no difference in cerebellar parvalbumin.
These results are supportive of a possible role for reduced GABAergic function within the locus ceruleus in essential tremor. The hypothesis that essential tremor represents early Parkinson’s disease was not supported as striatal dopaminergic markers were not reduced compared to control subjects.
tremor; pathology; GABA; norepinephrine
Dementia is a frequent complication of Parkinson’s disease (PD). About half of PD dementia (PDD) is hypothesized to be due to progression of the underlying Lewy body pathology into limbic regions and the cerebral cortex while the other half is thought to be due to coexistent Alzheimer’s disease. Clinically, however, these are indistinguishable. The spread of amyloid plaques to the striatum has been reported to be a sensitive and specific indicator of dementia due to Alzheimer’s disease (AD). The purpose of the present study was to determine if the presence of striatal plaques might also be a useful indicator of the presence of diagnostic levels of AD pathology within PD subjects. We analyzed neuropathologically-confirmed cases of PD without dementia (PDND, N = 31), PDD without AD (PDD, N = 31) and PD with dementia meeting clinicopathological criteria for AD (PDAD, N =40). The minimum diagnostic criterion for AD was defined as including a clinical history of dementia, moderate or frequent CERAD cortical neuritic plaque density and Braak neurofibrillary stage III–VI. Striatal amyloid plaque densities were determined using Campbell-Switzer and Thioflavine S stains. Striatal plaque densities were significantly higher in PDAD compared to PDD (p<0.001). The presence of striatal plaques was approximately 80% sensitive and 80% specific for predicting AD. In comparison, the presence of cerebral cortex plaques alone was highly sensitive (100%) but had poor specificity (48% to 55%). The results suggest that striatal amyloid imaging may be clinically useful for making the distinction between PDD and PDAD.
striatum; Lewy body; diagnosis; autopsy; neuropathology; biomarker
Amyloid-β (Aβ) peptides are intimately involved in the inflammatory pathology of atherosclerotic vascular disease (AVD) and Alzheimer's disease (AD). Although substantial amounts of these peptides are produced in the periphery, their role and significance to vascular disease outside the brain requires further investigation.
Amyloid-β peptides present in the walls of human aorta atherosclerotic lesions as well as activated and non-activated human platelets were isolated using sequential size-exclusion columns and HPLC reverse-phase methods. The Aβ peptide isolates were quantified by ELISA and structurally analyzed using MALDI-TOF mass spectrometry procedures.
Our experiments revealed that both aorta and platelets contained Aβ peptides, predominately Aβ40. The source of the Aβ pool in aortic atherosclerosis lesions is probably the activated platelets and/or vascular wall cells expressing APP/PN2. Significant levels of Aβ42 are present in the plasma, suggesting that this reservoir makes a minor contribution to atherosclerotic plaques.
Our data reveal that although aortic atherosclerosis and AD cerebrovascular amyloidosis exhibit clearly divergent end-stage manifestations, both vascular diseases share some key pathophysiological promoting elements and pathways. Whether they happen to be deposited in vessels of the central nervous system or atherosclerotic plaques in the periphery, Aβ peptides may promote and perhaps synergize chronic inflammatory processes which culminate in the degeneration, malfunction and ultimate destruction of arterial walls.
atherosclerosis; platelets; amyloid-beta; vascular inflammation; Alzheimer's disease; coagulation cascade
Banked tissue is essential to the study of neurological disease but using postmortem tissue introduces a number of possible confounds. Foremost amongst these are factors relating to variation in postmortem interval (PMI). Currently there are conflicting reports on how PMI affects overall RNA integrity, and very few reports of how gene expression is affected by PMI. We analyzed total RNA extracted from frozen cerebellar cortex from 79 deceased human subjects enrolled in the Banner Sun Health Research Institute Brain and Body Donation Program. The PMI, which ranged from 1.5 to 45 hours, correlated with overall RNA quality measures including RNA Integrity Number (RIN) (r = − 0.34, p = 0.002) and RNA quantitative yield (r = − 0.25, p = 0.02). Additionally, we determined the expression of 89 genes using a PCR-based gene expression array (RT2 ProfilerTM PCR Array: Human Alzheimer’s Disease; SABiosciencesTM, Frederick, MD). A greater proportion of genes had decreased rather than increased expression with increasing PMI (65/89 vs 20/89; p < 0.0001). Of these, transcripts from the genes ADAM9, LPL, PRKCG, and SERPINA3 had significantly decreased expression with increasing PMI (p < 0.01). No individual gene transcripts had significantly increased expression with increasing PMI. In conclusion, it is apparent that RNA degrades progressively with increasing PMI and that measurement of gene expression in brain tissue with longer PMI may give artificially low values. For tissue derived from autopsy, a short PMI optimizes its utility for molecular research.
RIN; RNA; postmortem; brain; gene expression; Alzheimer’s disease; neurological disease; research; methods
Down syndrome appears to be associated with a virtually certain risk of fibrillar amyloid-β (Aβ) pathology by the age of 40 and a very high risk of dementia at older ages. The positron emission tomography (PET) ligand florbetapir F18 has been shown to characterize fibrillar Aβ in the living human brain and to provide a close correlation with subsequent Aβ neuropathology in individuals proximate to and after the end of life. The extent to which the most frequently used PET ligands can be used to detect fibrillar Aβ in patients with Down syndrome remains to be determined.
To characterize PET estimates of fibrillar Aβ burden in a Down syndrome patient very close to the end of life and to compare them with neuropathologic assessment made after his death.
With the family’s informed consent, florbetapir PET was used to study a 55-year-old Down syndrome patient with Alzheimer disease near the end of life; his brain was donated for neuropathologic assessment when he died 14 days later. Visual ratings of cerebral florbetapir uptake were performed by trained readers who were masked to the patient’s diagnosis as part of a larger study, and an automated algorithm was used to characterize regional-to-cerebellar standard uptake value ratios in 6 cerebral regions of interest. Neuropathologic assessments were performed masked to the patient’s diagnosis or PET measurements.
Visual ratings and automated analyses of the PET image revealed a heavy fibrillar Aβ burden in cortical, striatal, and thalamic regions, similar to that reported for patients with late-onset Alzheimer disease. This matched neuropathologic findings of frequent neuritic and diffuse plaques, as well as frequent amyloid angiopathy, except for neuropathologically demonstrated frequent cerebellar diffuse plaques and amyloid angiopathy that were not detected by the PET scan.
Florbetapir PET can be used to detect increased cerebral-to-cerebellar fibrillar Aβ burden in a Down syndrome patient with Alzheimer disease, even in the presence of frequent amyloid angiopathy and diffuse plaques in the cerebellum. Additional studies are needed to determine the extent to which PET could be used to detect and to track fibrillar Aβ and to evaluate investigational Aβ-modifying treatments in the presymptomatic and symptomatic stages of Alzheimer disease.
Human induced pluripotent stem cells (iPSCs) have become an intriguing approach for neurological disease modeling, because neural lineage-specific cell types that retain the donors' complex genetics can be established in vitro. The statistical power of these iPSC-based models, however, is dependent on accurate diagnoses of the somatic cell donors; unfortunately, many neurodegenerative diseases are commonly misdiagnosed in live human subjects. Postmortem histopathological examination of a donor's brain, combined with premortem clinical criteria, is often the most robust approach to correctly classify an individual as a disease-specific case or unaffected control. In this study, we describe iPSCs generated from a skin biopsy collected postmortem during the rapid autopsy of a 75-year-old male, whole body donor, defined as an unaffected neurological control by both clinical and histopathological criteria. These iPSCs were established in a feeder-free system by lentiviral transduction of the Yamanaka factors, Oct3/4, Sox2, Klf4, and c-Myc. Selected iPSC clones expressed both nuclear and surface antigens recognized as pluripotency markers of human embryonic stem cells (hESCs) and were able to differentiate in vitro into neurons and glia. Statistical analysis also demonstrated that fibroblast proliferation was significantly affected by biopsy site, but not donor age (within an elderly cohort). These results provide evidence that autopsy donor-derived fibroblasts can be successfully reprogrammed into iPSCs, and may provide an advantageous approach for generating iPSC-based neurological disease models.
induced pluripotent stem cells; genetic disease models; diagnostics; neurodegenerative diseases; postmortem; autopsy; neural differentiation
Normal pressure hydrocephalus (NPH) is considered potentially treatable with the placement of a cerebrospinal fluid (CSF) shunt. Yet, the procedure has had variable success, particularly with respect to improving the cognitive impairment in NPH. The presence of neurologic co-morbidities, particularly Alzheimer's Disease (AD), may contribute to shunt responsiveness. Uncovering the extent to which AD and NPH co-occur has implications for diagnosis and treatment of NPH. Autopsy studies of patients with NPH during life would elucidate the frequency of such co-morbidities.
We conducted a search of the Sun Health Research Institute Brain Donation Program database between 1/1/1997 and 4/1/09 to identify all cases with neuropathologic evidence of dementia as well as those cases of clinically diagnosed NPH. We reviewed the medical records and brain findings of each NPH case.
Of the 761 cases autopsied over the study interval, 563 cases were found to have neuropathological evidence meeting criteria for a dementing illness. AD was found exclusively in 313/563 (56%) cases with 94/563 cases having a secondary diagnosis of dementia.
We identified 9/761 cases with a clinical diagnosis of NPH, all nine cases were among the 563 cases with neuropathology of dementing illness at autopsy, representing 1.6% (9/563). Upon review of brain autopsy reports, 8/9 (89%) cases were found to have AD and 1/9 (11%) had progressive supranuclear palsy. Review of the medical records of the nine NPH cases revealed the following clinical co-morbidities: 5/9 with AD; 1/9 with Parkinson's Disease (PD); 1/9 with Mild Cognitive Impairment (MCI); 1/9 with seizure disorder.
Given the findings of our study, we support the AD-NPH theory and posit that AD is a common pathological co-morbidity in the setting of NPH and may preclude cognitive improvement post-shunt placement. This may have influence on selection of cases for shunting in the future.
normal pressure hydrocephalus; Alzheimer's disease; cerebrospinal fluid shunt; autopsy study; dementia
A substantial body of evidence amassed from epidemiologic, correlative and experimental studies strongly associates atherosclerotic vascular disease (AVD) with Alzheimer's disease (AD). Depending on the precise interrelationship between AVD and AD, systematic application of interventions to maintain vascular health and function as a component of standard AD therapy offers the prospect of mitigating what is presently the inexorable course of dementia. To assess this hypothesis it is vital to rigorously establish the measures of AVD that are most strongly associated with an AD diagnosis.
A precise neuropathological diagnosis was established for all subjects using a battery of genetic, clinical, and histological methods. The severity of atherosclerosis in the circle of Willis (CW) was quantified by direct digitized measurement of arterial occlusion in postmortem specimens and compared between AD and non-demented control (NDC) groups by calculating a corresponding index of occlusion.
Atherosclerotic occlusion of the CW arteries was more extensive in the AD group than the NDC group. Statistically significant differences were also observed between control and AD groups with regard to Braak stage, total plaque score, total NFT score, total white matter rarefaction score, brain weight, MMSE scores and apolipoprotein E allelic frequencies.
Our results, combined with a consideration of the multifaceted impacts of impaired cerebral circulation, suggest an immediate need for prospective clinical trials to assess the efficacy of AD prevention using anti-atherosclerotic agents.
Alzheimer's disease; vascular dementia; intracranial atherosclerosis; circle of Willis; brain hypoperfusion
Amyloid imaging has identified cognitively normal older people with plaques as a group possibly at increased risk for developing Alzheimer’s disease-related dementia. It is important to begin to thoroughly characterize this group so that preventative therapies might be tested. Existing cholinotropic agents are a logical choice for preventative therapy as experimental evidence suggests that they are anti-amyloidogenic and clinical trials have shown that they delay progression of mild cognitive impairment to dementia. A detailed understanding of the status of the cortical cholinergic system in preclinical AD is still lacking, however. For more than 30 years, depletion of the cortical cholinergic system has been known to be one of the characteristic features of AD. Reports to date have suggested that some cholinergic markers are altered prior to cognitive impairment while others may show changes only at later stages of dementia. These studies have generally been limited by relatively small sample sizes, long postmortem intervals and insufficient definition of control and AD subjects by the defining histopathology. We therefore examined pre- and post-synaptic elements of the cortical cholinergic system in frontal and parietal cortex in 87 deceased subjects, including non-demented elderly with and without amyloid plaques as well as demented persons with neuropathologically-confirmed AD. Choline acetyltransferase (ChAT) activity was used as a presynaptic marker while displacement of 3H-pirenzepine binding by oxotremorine-M in the presence and absence of GppNHp was used to assess postsynaptic M1 receptor coupling. The results indicate that cortical ChAT activity as well as M1 receptor coupling are both significantly decreased in non-demented elderly subjects with amyloid plaques and are more pronounced in subjects with AD and dementia. These findings confirm that cortical cholinergic dysfunction in AD begins at the preclinical stage of disease and suggest that cholinotropic agents currently used for AD treatment are a logical choice for preventative therapy.
Alzheimer’s disease; cholinergic; muscarinic receptor; G-protein; amyloid imaging; preventative therapy; asymptomatic
We aimed to describe cases with incidental neuropathological findings of progressive supranuclear palsy (PSP) from the Banner Sun Health Research Institute Brain and Body Donation Program.
We performed a retrospective review of 277 subjects with longitudinal motor and neuropsychological assessments who came to autopsy. The mean Gallyas-positive PSP features grading for subjects with possible incidental neuropathological PSP was compared to those of subjects with clinically manifest disease.
There were 5 cases with histopathological findings suggestive of PSP, but no parkinsonism, dementia or movement disorder during life. Cognitive evaluation revealed 4 of the 5 cases to be cognitively normal; one case had amnestic mild cognitive impairment (MCI) in her last year of life. The mean age at death of the 5 cases was 88.9 years (range 80-94). All 5 individuals had histopathologic microscopic findings suggestive of PSP. Mean Gallyas-positive PSP features grading was significantly lower in subjects with possible incidental neuropathological PSP than subjects with clinical PSP, particularly in the subthalamic nucleus.
We present 5 patients with histopathological findings suggestive of PSP, without clinical PSP, dementia or parkinsonism during life. These incidental neuropathological PSP findings may represent the early or pre-symptomatic stage of PSP. The mean Gallyas-positive PSP features grading was significantly lower in possible incidental PSP than in clinical PSP, thus suggesting that a threshold of pathological burden needs to be reached within the typically affected areas in PSP before clinical signs and symptoms appear.
progressive supranuclear palsy; PSP; incidental; autopsy; parkinsonism; neuropathology
A sensitive immunohistochemical method for phosphorylated α-synuclein was used to stain sets of sections of spinal cord and tissue from 41 different sites in the bodies of 92 subjects, including 23 normal elderly, 7 with incidental Lewy body disease (ILBD), 17 with Parkinson’s disease (PD), 9 with dementia with Lewy bodies (DLB), 19 with Alzheimer’s disease with Lewy bodies (ADLB) and 17 with Alzheimer’s disease with no Lewy bodies (AD-NLB). The relative densities and frequencies of occurrence of phosphorylated α-synuclein histopathology (PASH) were tabulated and correlated with diagnostic category. The greatest densities and frequencies of PASH occurred in the spinal cord, followed by the paraspinal sympathetic ganglia, the vagus nerve, the gastrointestinal tract and endocrine organs. The frequency of PASH within other organs and tissue types was much lower. Spinal cord and peripheral PASH was most common in subjects with PD and DLB, where it appears likely that it is universally widespread. Subjects with ILBD had lesser densities of PASH within all regions, but had frequent involvement of the spinal cord and paraspinal sympathetic ganglia, with less-frequent involvement of end-organs. Subjects with ADLB had infrequent involvement of the spinal cord and paraspinal sympathetic ganglia with rare involvement of end-organs. Within the gastrointestinal tract, there was a rostrocaudal gradient of decreasing PASH frequency and density, with the lower esophagus and submandibular gland having the greatest involvement and the colon and rectum the lowest.
Parkinson’s disease; Parkinsonism; Dementia with Lewy bodies; Alzheimer’s disease; Incidental Lewy bodies; α-Synuclein; Spinal cord; Sympathetic nervous system; Peripheral nervous system; Autonomic nervous system; Enteric nervous system; Submandibular gland; Esophagus; Adrenal gland; Heart; Stomach; Gastrointestinal system
Epidemiological studies indicate a statistical linkage between atherosclerotic vascular disease (ATH) and Alzheimer's disease (AD). Autopsy studies of cardiac disease in AD have been few and inconclusive. In this report, clinical and gross anatomic measures of cardiac disease were compared in deceased human subjects with and without AD.
Clinically documented cardiovascular conditions from AD (n = 35) and elderly non-demented control subjects (n = 22) were obtained by review of medical records. Coronary artery stenosis and other gross anatomical measures, including heart weight, ventricular wall thickness, valvular circumferences, valvular calcifications and myocardial infarct number and volume were determined at autopsy.
Compared to non-demented age-similar control subjects, those with AD had significantly fewer total diagnosed clinical conditions (2.91 vs 4.18), decreased coronary artery stenosis (70.8 vs 74.8%), heart weight (402 vs 489 g for males; 319 vs 412 g for females) and valvular circumferences. Carriage of the Apolipoprotein E-ε4 allele did not influence the degree of coronary stenosis. Group differences in heart weight remained significant after adjustment for age, gender, body mass index and apolipoprotein E genotype while differences in coronary artery stenosis were significantly associated with body mass index alone.
The results are in agreement with an emerging understanding that, while midlife risk factors for ATH increase the risk for the later development of AD, once dementia begins, both risk factors and manifest disease diminish, possibly due to progressive weight loss with increasing dementia as well as disease involvement of the brain's vasomotor centers.
The diagnostic performance of several candidate cerebrospinal fluid (CSF) protein biomarkers of neuropathologically-confirmed Alzheimer’s disease (AD), non-demented (ND) elderly controls and non-AD dementias (NADD) was assessed. Candidate markers were selected on the basis of initial 2-dimensional gel electrophoresis studies or by literature review. Markers selected by the former method included apolipoprotein A-1 (ApoA1), hemopexin (HPX), transthyretin (TTR) and pigment epithelium-derived factor (PEDF) while markers identified from the literature included Aβ1–40, Aβ1–42, total tau, phosphorylated tau, α-1 acid glycoprotein (A1GP), haptoglobin, zinc α-2 glycoprotein (Z2GP) and apolipoprotein E (ApoE). Ventricular CSF concentrations of the markers were measured by ELISA. The concentrations of Aβ1–42, ApoA1, A1GP, ApoE, HPX and Z2GP differed significantly among AD, ND and NADD subjects. Logistic regression analysis for the diagnostic discrimination of AD from ND found that Aβ1–42, ApoA1 and HPX each had significant and independent associations with diagnosis. The CSF concentrations of these three markers distinguished AD from ND subjects with 84% sensitivity and 72% specificity, with 78% of subjects correctly classified. By comparison, using Aβ1–42 alone gave 79% sensitivity and 61% specificity, with 68% of subjects correctly classified. For the diagnostic discrimination of AD from NADD, only the concentration of Aβ1–42 was significantly related to diagnosis, with a sensitivity of 58%, specificity of 86% and 86% correctly classified. The results indicate that for the discrimination of AD from ND control subjects, measurement of a set of markers including Aβ1–42, ApoA1 and HPX improved diagnostic performance over that obtained by measurement of Aβ1–42 alone. For the discrimination of AD from NADD subjects, measurement of Aβ1–42 alone was superior.
Alzheimer’s disease; non-Alzheimer’s disease dementias; cerebrospinal fluid; biomarkers; ELISA; Aβ; tau; apolipoprotein A-1; α-1 acid glycoprotein; haptoglobin; hemopexin; transthyretin; pigment epithelium-derived factor; zinc α-2 glycoprotein and apolipoprotein E
A crucial need exists for reliable Alzheimer’s disease (AD) diagnostic and prognostic tests. Given its intimate communication with the brain, the cerebrospinal fluid (CSF) has been surveyed intensively for reliable AD biomarkers. The heterogeneity of AD pathology and the unavoidable difficulties associated with the clinical diagnosis and differentiation of this dementia from other pathologies have confounded biomarker studies in antemortem CSF samples. Using postmortem ventricular CSF (V-CSF) pools, two-dimensional difference gel electrophoresis (2D DIGE) analyses revealed a set of proteins that showed significant differences between neuropathologically-diagnosed AD and elderly non-demented controls (NDC), as well as subjects with non-AD dementias. The 2D DIGE system identified a set of 21 different protein biomarkers. This panel of proteins probably reflects fundamental pathological changes that are divergent from both normal aging and non-AD dementias.
Alzheimer’s disease; cerebrospinal fluid; proteomics; DIGE; biomarkers
Subjects with Parkinson's disease (PD) frequently develop dementia with greater than one-third meeting neuropathologic diagnostic criteria for Alzheimer's disease (AD). The objective is to identify clinical and neuropathological differences between PDD (PD with dementia) subjects, with and without coexistent AD pathology. Neuropathologic examination was available on subjects diagnosed by clinicopathologic criteria with PDD-AD (N = 23) and PDD+AD (N = 28). A small subset of subjects with PDD-AD and PDD+AD had received at least one standardized neuropsychological assessment. PDD+AD subjects were significantly older at age of PD onset and death, progressed to onset of dementia in less time, and had a shorter duration of PD symptoms prior to the onset of dementia. Education, responsiveness of L-Dopa and dopaminergic medications, presence of cognitive fluctuations and hallucinations, mean MMSE, GDS, FAST and UPDRS scores did not differ significantly between the two groups. The PDD+AD group had significantly greater total plaques, neuritic plaques, total tangles, and Braak stages compared to PDD-AD. This study suggests that it is difficult to distinguish PDD+AD and PDD-AD on the basis of movement, clinical, and neuropsychological assessment. PDD-AD and PDD+AD have similar degrees of dementia and approximately half of PDD subjects have enough AD pathology to attain a neuropathological diagnosis of AD. PDD can develop in the absence of significant Alzheimer pathology.
Parkinson' disease with dementia; Alzheimer's Disease; Dementia with Lewy Bodies; assessment of dementia
The two current major staging systems in use for Lewy body disorders fail to classify up to 50% of subjects. Both systems do not allow for large numbers of subjects who have Lewy-type α-synucleinopathy (LTS) confined to the olfactory bulb or who pass through a limbic-predominant pathway that at least initially bypasses the brainstem. The results of the current study, based on examination of a standard set of 10 brain regions from 417 subjects stained immunohistochemically for α-synuclein, suggest a new staging system that, in this study, allows for the classification of all subjects with Lewy body disorders. The autopsied subjects included elderly subjects with Parkinson’s disease, dementia with Lewy bodies, incidental Lewy body disease and Alzheimer’s disease with Lewy bodies, as well as comparison groups without Lewy bodies. All subjects were classifiable into one of the following stages: I. Olfactory Bulb Only; IIa Brainstem Predominant; IIb Limbic Predominant; III Brainstem and Limbic; IV Neocortical. Progression of subjects through these stages was accompanied by a generally stepwise worsening in terms of striatal tyrosine hydroxylase concentration, substantia nigra pigmented neuron loss score, Mini Mental State Examination score and score on the Unified Parkinson’s Disease Rating Scale Part 3. Additionally there were significant correlations between these measures and LTS density scores. It is suggested that the proposed staging system would improve on its predecessors by allowing classification of a much greater proportion of cases.
Parkinson’s disease; parkinsonism; dementia with Lewy bodies; Alzheimer’s disease; incidental Lewy bodies; α-synuclein; olfactory bulb; amgydala; limbic; brainstem; neocortex
Involvement of the olfactory bulb by Lewy-type α-synucleinopathy (LTS) is known to occur at an early stage of Parkinson's disease (PD) and Lewy body disorders and is therefore of potential usefulness diagnostically. An accurate estimate of the specificity and sensitivity of this change has not previously been available. We performed immunohistochemical α-synuclein staining of the olfactory bulb in 328 deceased individuals. All cases had received an initial neuropathological examination that included α-synuclein immunohistochemical staining on sections from brainstem, limbic and neocortical regions, but excluded olfactory bulb. These cases had been classified based on their clinical characteristics and brain regional distribution and density of LTS, as PD, dementia with Lewy bodies (DLB), Alzheimer's disease with LTS (ADLS), Alzheimer's disease without LTS (ADNLS), incidental Lewy body disease (ILBD) and elderly control subjects. The numbers of cases found to be positive and negative, respectively, for olfactory bulb LTS were: PD 55/3; DLB 34/1; ADLS 37/5; ADNLS 19/84; ILBD 14/7; elderly control subjects 5/64. The sensitivities and specificities were, respectively: 95 and 91% for PD versus elderly control; 97 and 91% for DLB versus elderly control; 88 and 91% for ADLS versus elderly control; 88 and 81% for ADLS versus ADNLS; 67 and 91% for ILBD versus elderly control. Olfactory bulb synucleinopathy density scores correlated significantly with synucleinopathy scores in all other brain regions (Spearman R values between 0.46 and 0.78) as well as with scores on the Mini-Mental State Examination and Part 3 of the unified Parkinson's Disease Rating Scale (Spearman R −0.27, 0.35, respectively). It is concluded that olfactory bulb LTS accurately predicts the presence of LTS in other brain regions. It is suggested that olfactory bulb biopsy be considered to confirm the diagnosis in PD subjects being assessed for surgical therapy.
Parkinson's disease, surgery; Deep brain stimulation; Gene therapy; Transplantation; Dementia with Lewy bodies, diagnosis, therapy, clinical trial; α-Synuclein, Lewy bodies, incidental Lewy body disease; Biopsy; Olfactory bulb
Incidental Lewy body disease (ILBD) is the term used when Lewy bodies are found in the nervous system of subjects without clinically documented parkinsonism or dementia. The prevalence of ILBD in the elderly population has been estimated at between 3.8 and 30%, depending on subject age and anatomical site of sampling. It has been speculated that ILBD represents the preclinical stage of Parkinson’s disease (PD) and/or dementia with Lewy bodies (DLB). Studies of ILBD could potentially identify early diagnostic signs of these disorders. At present, however, it is impossible to know whether ILBD is a precursor to PD or DLB or is just a benign finding of normal aging. We hypothesized that, if ILBD represents an early stage of PD or DLB, it should be associated with depletion of striatal dopaminergic markers. Eleven subjects with ILBD and 27 control subjects were studied. The ILBD subjects ranged in age from 74 to 96 years (mean 86.5) while the control subjects’ age ranged from 75 to 102 years (mean 86.7). Controls and subjects did not differ in terms of age, postmortem interval, gender distribution, medical history conditions, brain weight, neuritic plaque density or Braak neurofibrillary stage. Quantitative ELISA measurement of striatal tyrosine hydroxylase (TH), the principal enzyme for dopamine synthesis, showed a 49.8% (P = 0.01) reduction in ILBD cases, as compared with control cases. The finding suggests that ILBD is not a benign condition but is likely a precursor to PD and/or DLB.
Striatum; Dopamine; Parkinson’s disease; Lewy bodies; Pathogenesis; Aging
Alzheimer’s disease (AD) is characterized by overproduction of Aβ derived from APP cleavage via β- and γ-secretase pathway. Recent evidence has linked altered cholesterol metabolism to AD pathogenesis. In this study, we show that AD brain had significant cholesterol retention and high β- and γ-secretase activities as compared to age-matched non-demented controls (ND). Over one-half of AD patients had an apoE4 allele but none of the ND. β- and γ-secretase activities were significantly stimulated in vitro by 40 and 80 µm cholesterol in AD and ND brains, respectively. Both secretase activities in AD brain were more sensitive to cholesterol (40 µm) than those of ND (80 µm). Filipin-stained cholesterol overlapped with BACE and Aβ in AD brain sections. Cholesterol (10–80 µM) added to N2a cultures significantly increased cellular cholesterol, β- and γ-secretase activities and Aβ secretion. Similarly, addition of cholesterol (20–80 µM) to cell lysates stimulated both in vitro secretase activities. Ergosterol slightly decreased β-secretase activity at 20–80 µM, but strongly inhibited γ-secretase activity at 40 µM. Cholesterol depletion reduced cellular cholesterol, β-secretase activity and Aβ secretion. Transcription factor profiling shows that several key nuclear receptors involving cholesterol metabolism were significantly altered in AD brain, including decreased LXR-β, PPAR and TR, and increased RXR. Treatment of N2a cells with LXR, RXR or PPAR agonists strongly stimulated cellular cholesterol efflux to HDL and reduced cellular cholesterol and β-/γ-secretase activities. This study provides direct evidence that cholesterol homeostasis is impaired in AD brain and suggests that altered levels or activities of nuclear receptors may contribute to cholesterol retention which likely enhances β- and γ-secretase activities and Aβ production in human brain.
Alzheimer’disease; Cholesterol retention; Nuclear receptors; β- and γ-secretases; Aβ- production
The Brain Donation Program at Sun Health Research Institute has been in continual operation since 1987, with over 1000 brains banked. The population studied primarily resides in the retirement communities of northwest metropolitan Phoenix, Arizona. The Institute is affiliated with Sun Health, a nonprofit community-owned and operated health care provider. Subjects are enrolled prospectively to allow standardized clinical assessments during life. Funding comes primarily from competitive grants. The Program has made short postmortem brain retrieval a priority, with a 2.75-h median postmortem interval for the entire collection. This maximizes the utility of the resource for molecular studies; frozen tissue from approximately 82% of all cases is suitable for RNA studies. Studies performed in-house have shown that, even with very short postmortem intervals, increasing delays in brain retrieval adversely affect RNA integrity and that cerebrospinal fluid pH increases with postmortem interval but does not predict tissue viability.
Brain banking; Neuropathology; Postmortem; Autopsy; Tissue banking; RNA; pH; Cerebrospinal fluid; Postmortem interval
The use of α-synuclein immunohistochemistry has altered our concepts of the cellular pathology, anatomical distribution and prevalence of Lewy body disorders. However, the diversity of methodology between laboratories has led to some inconsistencies in the literature. Adoption of uniformly sensitive methods may resolve some of these differences. Eight different immunohistochemical methods for demonstrating α-synuclein pathology, developed in eight separate expert laboratories, were evaluated for their sensitivity for neuronal elements affected by human Lewy body disorders. Identical test sets of formalin-fixed, paraffin-embedded sections from subjects diagnosed neuropathologically with or without Lewy body disorders were stained with the eight methods and graded by three observers for specific and nonspecific staining. The methods did not differ significantly in terms of Lewy body counts, but varied considerably in their ability to reveal neuropil elements such as fibers and dots. One method was clearly superior for revealing these neuropil elements and the critical factor contributing to its high sensitivity was considered to be its use of proteinase K as an epitope retrieval method. Some methods, however, achieved relatively high sensitivities with optimized formic acid protocols combined with a hydrolytic step. One method was developed that allows high sensitivity with commercially available reagents.