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1.  Reporting standards for studies of diagnostic test accuracy in dementia 
Neurology  2014;83(4):364-373.
Objective:
To provide guidance on standards for reporting studies of diagnostic test accuracy for dementia disorders.
Methods:
An international consensus process on reporting standards in dementia and cognitive impairment (STARDdem) was established, focusing on studies presenting data from which sensitivity and specificity were reported or could be derived. A working group led the initiative through 4 rounds of consensus work, using a modified Delphi process and culminating in a face-to-face consensus meeting in October 2012. The aim of this process was to agree on how best to supplement the generic standards of the STARD statement to enhance their utility and encourage their use in dementia research.
Results:
More than 200 comments were received during the wider consultation rounds. The areas at most risk of inadequate reporting were identified and a set of dementia-specific recommendations to supplement the STARD guidance were developed, including better reporting of patient selection, the reference standard used, avoidance of circularity, and reporting of test-retest reliability.
Conclusion:
STARDdem is an implementation of the STARD statement in which the original checklist is elaborated and supplemented with guidance pertinent to studies of cognitive disorders. Its adoption is expected to increase transparency, enable more effective evaluation of diagnostic tests in Alzheimer disease and dementia, contribute to greater adherence to methodologic standards, and advance the development of Alzheimer biomarkers.
doi:10.1212/WNL.0000000000000621
PMCID: PMC4115600  PMID: 24944261
2.  Blood pressure decrease correlates with tau pathology and memory decline in hypertensive elderly 
Neurobiology of aging  2013;35(1):64-71.
In hypertension, cerebral blood flow regulation limits are changed, and the threshold for blood pressure at which perfusion is safely maintained is higher. This shift may increase the brain's vulnerability to lower blood pressure in subjects with vascular disease. We investigated whether longitudinal reduction in mean arterial pressure (MAP) was related to changes in CSF biomarkers of Alzheimer's disease in a group of cognitively healthy elderly with and without hypertension (HTN). The relationships between MAP, memory decline and hippocampal atrophy were also examined. Seventy-seven subjects (age 63.4±9.4, range 44-86 years; education 16.9±2.1, range 10-22 years; 60% women) were assessed twice, 2±0.5 years apart. At both time points, all subjects underwent full medical and neuropsychological evaluations, lumbar punctures and MRI examinations. Twenty-five subjects had HTN. Hypertensive and normotensive subjects did not differ in their CSF biomarkers, hippocampal volumes or memory scores at baseline. In the entire study group, the increase in p-tau181 was associated with a decline in verbal episodic memory (ß=−.30, p=.01) and hippocampal volume reduction (ß=−.27, p=.02). However, longitudinal decrease in MAP was related to memory decline (β=0.50, p=.01) and an increase in p-tau181 (β=−0.50, p=.01) only in subjects with hypertension. Our findings suggest that the hypertensive group may be sensitive to blood pressure reductions.
doi:10.1016/j.neurobiolaging.2013.06.011
PMCID: PMC3799812  PMID: 23969178
3.  Biomarkers in Amyloid-β Immunotherapy Trials in Alzheimer's Disease 
Neuropsychopharmacology  2013;39(1):189-201.
Drug candidates directed against amyloid-β (Aβ) are mainstream in Alzheimer's disease (AD) drug development. Active and passive Aβ immunotherapy is the principle that has come furthest, both in number and in stage of clinical trials. However, an increasing number of reports on major difficulties in identifying any clinical benefit in phase II–III clinical trials on this type of anti-Aβ drug candidates have caused concern among researchers, pharmaceutical companies, and other stakeholders. This has provided critics of the amyloid cascade hypothesis with fire for their arguments that Aβ deposition may merely be a bystander, and not the cause, of the disease or that the amyloid hypothesis may only be valid for the familial form of AD. On the other hand, most researchers argue that it is the trial design that will need refinement to allow for identifying a positive clinical effect of anti-Aβ drugs. A consensus in the field is that future trials need to be performed in an earlier stage of the disease and that biomarkers are essential to guide and facilitate drug development. In this context, it is reassuring that, in contrast to most brain disorders, research advances in the AD field have led to both imaging (magnetic resonance imaging (MRI) and PET) and cerebrospinal fluid (CSF) biomarkers for the central pathogenic processes of the disease. AD biomarkers will have a central role in future clinical trials to enable early diagnosis, and Aβ biomarkers (CSF Aβ42 and amyloid PET) may be essential to allow for testing a drug on patients with evidence of brain Aβ pathology. Pharmacodynamic Aβ and amyloid precursor protein biomarkers will be of use to verify target engagement of a drug candidate in humans, thereby bridging the gap between mechanistic data from transgenic AD models (that may not be relevant to the neuropathology of human AD) and large and expensive phase III trials. Last, downstream biomarker evidence (CSF tau proteins and MRI volumetry) that the drug ameliorates neurodegeneration will, together with beneficial clinical effects on cognition and functioning, be essential for labeling an anti-Aβ drug as disease modifying.
doi:10.1038/npp.2013.154
PMCID: PMC3857643  PMID: 23799530
Alzheimer's Disease; biomarker; cerebrospinal fluid; Cognition; mild cognitive impairment (MCI); Neurodegeneration; Neuroprotection; Neurology; phosphorylated tau; tau protein; Alzheimer's disease; biomarker; amyloid-β (Aβ); cerebrospinal fluid; clinical trial; theragnostic
4.  Cerebrospinal Fluid (CSF) Neuronal Biomarkers across the Spectrum of HIV Infection: Hierarchy of Injury and Detection 
PLoS ONE  2014;9(12):e116081.
The character of central nervous system (CNS) HIV infection and its effects on neuronal integrity vary with evolving systemic infection. Using a cross-sectional design and archived samples, we compared concentrations of cerebrospinal fluid (CSF) neuronal biomarkers in 143 samples from 8 HIV-infected subject groups representing a spectrum of untreated systemic HIV progression and viral suppression: primary infection; four groups of chronic HIV infection neuroasymptomatic (NA) subjects defined by blood CD4+ T cells of >350, 200–349, 50–199, and <50 cells/µL; HAD; treatment-induced viral suppression; and ‘elite’ controllers. Samples from 20 HIV-uninfected controls were also examined. The neuronal biomarkers included neurofilament light chain protein (NFL), total and phosphorylated tau (t-tau, p-tau), soluble amyloid precursor proteins alpha and beta (sAPPα, sAPPβ) and amyloid beta (Aβ) fragments 1–42, 1–40 and 1–38. Comparison of the biomarker changes showed a hierarchy of sensitivity in detection and suggested evolving mechanisms with progressive injury. NFL was the most sensitive neuronal biomarker. Its CSF concentration exceeded age-adjusted norms in all HAD patients, 75% of NA CD4<50, 40% of NA CD4 50–199, and 42% of primary infection, indicating common neuronal injury with untreated systemic HIV disease progression as well as transiently during early infection. By contrast, only 75% of HAD subjects had abnormal CSF t-tau levels, and there were no significant differences in t-tau levels among the remaining groups. sAPPα and β were also abnormal (decreased) in HAD, showed less marked change than NFL with CD4 decline in the absence of HAD, and were not decreased in PHI. The CSF Aβ peptides and p-tau concentrations did not differ among the groups, distinguishing the HIV CNS injury profile from Alzheimer's disease. These CSF biomarkers can serve as useful tools in selected research and clinical settings for patient classification, pathogenetic analysis, diagnosis and management.
doi:10.1371/journal.pone.0116081
PMCID: PMC4277428  PMID: 25541953
5.  Genetic Variants and Related Biomarkers in Sporadic Alzheimer’s Disease 
From a neuropathological perspective, elderly patients who die with a clinical diagnosis of sporadic Alzheimer’s disease (AD) are a heterogeneous group with several different pathologies contributing to the AD phenotype. This poses a challenge when searching for low effect size susceptibility genes for AD. Further, control groups may be contaminated by significant numbers of preclinical AD patients, which also reduces the power of genetic association studies. Here, we discuss how cerebrospinal fluid and imaging biomarkers can be used to increase the chance of finding novel susceptibility genes and as a means to study the functional consequences of risk alleles.
doi:10.1007/s40142-014-0062-6
PMCID: PMC4317514  PMID: 25664224
Cerebrospinal fluid; Imaging biomarkers; Novel susceptibility genes; Risk alleles
6.  Genetic associations of Nrf2-encoding NFE2L2 variants with Parkinson’s disease – a multicenter study 
BMC Medical Genetics  2014;15:131.
Background
The transcription factor Nrf2, encoded by the NFE2L2 gene, is an important regulator of the cellular protection against oxidative stress. Parkinson’s disease is a neurodegenerative disease highly associated with oxidative stress. In a previously published study, we reported associations of NFE2L2 haplotypes with risk and age at onset of idiopathic Parkinson’s disease in a Swedish discovery material and a Polish replication material. Here, we have extended the replication study and performed meta-analyses including the Polish material and four new independent European patient-control materials. Furthermore, all SNPs included in the haplotype windows were investigated individually for associations with Parkinson’s disease in meta-analyses including all six materials.
Methods
Totally 1038 patients and 1600 control subjects were studied. Based on previous NFE2L2 haplotype associations with Parkinson’s disease, five NFE2L2 tag SNPs were genotyped by allelic discrimination and three functional NFE2L2 promoter SNPs were genotyped by sequencing. The impact of individual SNPs and haplotypes on risk and age at onset of Parkinson’s disease were investigated in each material individually and in meta-analyses of the obtained results.
Results
Meta-analyses of NFE2L2 haplotypes showed association of haplotype GAGCAAAA, including the fully functional promoter haplotype AGC, with decreased risk (OR = 0.8 per allele, p = 0.012) and delayed onset (+1.1 years per allele, p = 0.048) of Parkinson’s disease. These results support the previously observed protective effect of this haplotype in the first study. Further, meta-analyses of the SNPs included in the haplotypes revealed four NFE2L2 SNPs associated with age at onset of Parkinson’s disease (rs7557529 G > A, −1.0 years per allele, p = 0.042; rs35652124 A > G, −1.1 years per allele, p = 0.045; rs2886161 A > G, −1.2 years per allele, p = 0.021; rs1806649 G > A, +1.2 years per allele, p = 0.029). One of these (rs35652124) is a functional SNP located in the NFE2L2 promoter. No individual SNP was associated with risk of Parkinson’s disease.
Conclusion
Our results support the hypothesis that variation in the NFE2L2 gene, encoding a central protein in the cellular protection against oxidative stress, may contribute to the pathogenesis of Parkinson’s disease. Functional studies are now needed to explore these results further.
Electronic supplementary material
The online version of this article (doi:10.1186/s12881-014-0131-4) contains supplementary material, which is available to authorized users.
doi:10.1186/s12881-014-0131-4
PMCID: PMC4335439  PMID: 25496089
Parkinson’s disease; PD; Nrf2; NFE2L2; Meta-analysis; Multicenter; SNP; Haplotype; Risk factor
7.  Genetic analysis implicates APOE, SNCA and suggests lysosomal dysfunction in the etiology of dementia with Lewy bodies 
Human molecular genetics  2014;23(23):6139-6146.
Clinical and neuropathological similarities between dementia with Lewy bodies (DLB), Parkinson’s and Alzheimer’s diseases (PD and AD, respectively) suggest that these disorders may share etiology. To test this hypothesis, we have performed an association study of 54 genomic regions, previously implicated in PD or AD, in a large cohort of DLB cases and controls. The cohort comprised 788 DLB cases and 2624 controls. To minimize the issue of potential misdiagnosis, we have also performed the analysis including only neuropathologically proven DLB cases (667 cases). The results show that the APOE is a strong genetic risk factor for DLB, confirming previous findings, and that the SNCA and SCARB2 loci are also associated after a study-wise Bonferroni correction, although these have a different association profile than the associations reported for the same loci in PD. We have previously shown that the p.N370S variant in GBA is associated with DLB, which, together with the findings at the SCARB2 locus, suggests a role for lysosomal dysfunction in this disease. These results indicate that DLB has a unique genetic risk profile when compared with the two most common neurodegenerative diseases and that the lysosome may play an important role in the etiology of this disorder. We make all these data available.
doi:10.1093/hmg/ddu334
PMCID: PMC4222357  PMID: 24973356
8.  SNAP-25 is a promising novel cerebrospinal fluid biomarker for synapse degeneration in Alzheimer’s disease 
Background
Synaptic degeneration is an early pathogenic event in Alzheimer’s disease, associated with cognitive impairment and disease progression. Cerebrospinal fluid biomarkers reflecting synaptic integrity would be highly valuable tools to monitor synaptic degeneration directly in patients. We previously showed that synaptic proteins such as synaptotagmin and synaptosomal-associated protein 25 (SNAP-25) could be detected in pooled samples of cerebrospinal fluid, however these assays were not sensitive enough for individual samples.
Results
We report a new strategy to study synaptic pathology by using affinity purification and mass spectrometry to measure the levels of the presynaptic protein SNAP-25 in cerebrospinal fluid. By applying this novel affinity mass spectrometry strategy on three separate cohorts of patients, the value of SNAP-25 as a cerebrospinal fluid biomarker for synaptic integrity in Alzheimer’s disease was assessed for the first time. We found significantly higher levels of cerebrospinal fluid SNAP-25 fragments in Alzheimer’s disease, even in the very early stages, in three separate cohorts. Cerebrospinal fluid SNAP-25 differentiated Alzheimer’s disease from controls with area under the curve of 0.901 (P < 0.0001).
Conclusions
We developed a sensitive method to analyze SNAP-25 levels in individual CSF samples that to our knowledge was not possible previously. Our results support the notion that synaptic biomarkers may be important tools for early diagnosis, assessment of disease progression, and to monitor drug effects in treatment trials.
Electronic supplementary material
The online version of this article (doi:10.1186/1750-1326-9-53) contains supplementary material, which is available to authorized users.
doi:10.1186/1750-1326-9-53
PMCID: PMC4253625  PMID: 25418885
Alzheimer’s disease; Biomarker; Cerebrospinal fluid; SNAP-25; SNARE proteins; Mass spectrometry; Immunopurification; Selected reaction monitoring
9.  β-site amyloid precursor protein-cleaving enzyme 1(BACE1) inhibitor treatment induces Aβ5-X peptides through alternative amyloid precursor protein cleavage 
Introduction
The β-secretase enzyme, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1), cleaves amyloid precursor protein (APP) in the first step in β-amyloid (Aβ) peptide production. Thus, BACE1 is a key target for candidate disease-modifying treatment of Alzheimer’s disease. In a previous exploratory Aβ biomarker study, we found that BACE1 inhibitor treatment resulted in decreased levels of Aβ1-34 together with increased Aβ5-40, suggesting that these Aβ species may be novel pharmacodynamic biomarkers in clinical trials. We have now examined whether the same holds true in humans.
Methods
In an investigator-blind, placebo-controlled and randomized study, healthy subjects (n =18) were randomly assigned to receive a single dose of 30 mg of LY2811376 (n =6), 90 mg of LY2811376 (n =6), or placebo (n =6). We used hybrid immunoaffinity-mass spectrometry (HI-MS) and enzyme-linked immunosorbent assays to monitor a variety of Aβ peptides.
Results
Here, we demonstrate dose-dependent changes in cerebrospinal fluid (CSF) Aβ1-34, Aβ5-40 and Aβ5-X after treatment with the BACE1-inhibitor LY2811376. Aβ5-40 and Aβ5-X increased dose-dependently, as reflected by two independent methods, while Aβ1-34 dose-dependently decreased.
Conclusion
Using HI-MS for the first time in a study where subjects have been treated with a BACE inhibitor, we confirm that CSF Aβ1-34 may be useful in clinical trials on BACE1 inhibitors to monitor target engagement. Since it is less hydrophobic than longer Aβ species, it is less susceptible to preanalytical confounding factors and may thus be a more stable marker. By independent measurement techniques, we also show that BACE1 inhibition in humans is associated with APP-processing into N-terminally truncated Aβ peptides via a BACE1-independent pathway.
Trial registration
ClinicalTrials.gov NCT00838084. Registered: First received: January 23, 2009, Last updated: July 14, 2009, Last verified: July 2009.
doi:10.1186/s13195-014-0075-0
PMCID: PMC4233234  PMID: 25404952
10.  Cerebrovascular Biomarker Profile Is Related to White Matter Disease and Ventricular Dilation in a LADIS Substudy 
Background
Small vessel disease (SVD) represents a common often progressive condition in elderly people contributing to cognitive disability. The relationship between cerebrospinal fluid (CSF) biomarkers and imaging correlates of SVD was investigated, and the findings were hypothesized to be associated with a neuropsychological profile of SVD.
Methods
CSF SVD-related biomarkers [neurofilament light (NF-L), myelin basic protein (MBP), soluble amyloid precursor protein-β (sAPPβ), matrix metalloproteinases (MMPs), and tissue inhibitor of metalloproteinase (TIMP)] were analysed in 46 non-demented elderly with imaging findings of SVD. We assessed the relationship between the CSF biomarkers and white matter hyperintensity (WMH) volume, diffusion-weighted imaging and atrophy as well as their association with neuropsychological profiles.
Results
The WMH volume correlated with ventricular dilation, which was associated with executive function and speed and attention. Increased WMH and ventricular dilation were related to increased CSF levels of TIMP-1, NF-L and MBP and to decreased sAPPβ. A positive correlation was found between the CSF biomarker MMP-9 and WMH progression.
Conclusions
The link between progressive WMH and MMP-9 suggests an involvement of the enzyme in white matter degeneration. CSF TIMP-1, NF-L, MBP and sAPPβ may function as biological markers of white matter damage.
doi:10.1159/000366119
PMCID: PMC4255994  PMID: 25493088
Biomarkers; Cerebrospinal fluid; Matrix metalloproteinases; Myelin basic protein; Neurofilament; Ventricular dilation; White matter disease
11.  Fluid Biomarkers in Alzheimer Disease 
Research progress has provided detailed understanding of the molecular pathogenesis of Alzheimer disease (AD). This knowledge has been translated into new drug candidates with putative disease-modifying effects, which are now being tested in clinical trials. The promise of effective therapy has created a great need for biomarkers able to detect AD in the predementia phase, because drugs will probably be effective only if neurodegeneration is not too advanced. In this chapter, cerebrospinal fluid (CSF) and plasma biomarkers are reviewed. The core CSF biomarkers total tau (T-tau), phosphorylated tau (P-tau) and the 42 amino acid form of β-amyloid (Aβ42) reflect AD pathology, and have high diagnostic accuracy to diagnose AD with dementia and prodromal AD in mild cognitive impairment cases. The rationale for the use of CSF biomarkers to identify and monitor the mechanism of action of new drug candidates is also outlined in this chapter.
To effectively treat Alzheimer disease, biomarkers to diagnose the disease in the predementia phase are needed. Biomarkers from cerebrospinal fluid and plasma (e.g., tau and amyloid-β) show excellent diagnostic performance.
doi:10.1101/cshperspect.a006221
PMCID: PMC3426814  PMID: 22951438
12.  Evolving Character of Chronic Central Nervous System HIV Infection 
Seminars in neurology  2014;34(1):7-13.
Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system (CNS) begins early in systemic infection and continues throughout its untreated course. Despite a common cerebrospinal fluid inflammatory response, it is usually neurologically asymptomatic for much of this course, but can evolve in some individuals to HIV-associated dementia (HAD), a severe encephalopathy with characteristic cognitive and motor dysfunction. While widespread use of combination antiretroviral therapy (ART) has led to a marked decline in both the CNS infection and its neurologic severe consequence, HAD continues to afflict individuals presenting with advanced systemic infection in the developed world and a larger number in resource-poor settings where ART is more restricted. Additionally, milder CNS injury and dysfunction have broader prevalence, including in those treated with ART. Here we review the history and evolving nomenclature of HAD, its viral pathogenesis, clinical presentation and diagnosis, and treatment.
doi:10.1055/s-0034-1372337
PMCID: PMC4120280  PMID: 24715483
HIV; dementia; treatment; brain; inflammation; cerebrospinal fluid; biomarkers
13.  The role of clusterin in amyloid-β associated neurodegeneration 
JAMA neurology  2014;71(2):180-187.
Importance
Converging evidence indicates that clusterin, a chaperone glycoprotein, influences Alzheimer's disease (AD) neurodegeneration. However, the precise role of clusterin in AD pathogenesis is still not well understood.
Objective
To elucidate the relationship between clusterin, amyloid-β (Aβ), p-tau, and rate of brain atrophy over time among non-demented older individuals.
Design
A longitudinal cohort of cognitively normal older participants (HC) and individuals with mild cognitive impairment (MCI) assessed with baseline lumbar puncture and longitudinal structural MRI.
Setting
Research centers across the United States and Canada.
Participants
We examined 241 non-demented older individuals (91 participants with a Clinical Dementia Rating (CDR) of 0 and 150 individuals with a CDR of 0.5).
Main Outcome Measures
Using linear mixed effects models, we investigated interactions between CSF clusterin, CSF Aβ1-42 and CSF p-tau181p on atrophy rate of the entorhinal cortex and hippocampus.
Results
Across all participants, we found a significant interaction between CSF clusterin and CSF Aβ1-42 on entorhinal cortex atrophy rate, but not on hippocampal atrophy rate. CSF clusterin was associated with entorhinal cortex atrophy rate among CSF Aβ1-42 positive individuals, but not among CSF Aβ1-42 negative individuals. In secondary analyses, we found significant interactions between CSF Aβ1-42 and CSF clusterin and CSF Aβ1-42 and CSF p-tau181p on entorhinal cortex atrophy rate. We found similar results in subgroup analyses within the MCI and HC cohorts.
Conclusions and Relevance
In non-demented older individuals, Aβ-associated volume loss occurs in the presence of elevated clusterin. The effect of clusterin on Aβ-associated brain atrophy is not confounded or explained by p-tau. These findings implicate a potentially important role for clusterin in the earliest stages of the AD neurodegenerative process and suggest independent effects of clusterin and p-tau on Aβ-associated volume loss.
doi:10.1001/jamaneurol.2013.4560
PMCID: PMC4118752  PMID: 24378367
14.  Increased Levels of Chitotriosidase and YKL-40 in Cerebrospinal Fluid from Patients with Alzheimer's Disease 
Background
The cerebrospinal fluid (CSF) biomarkers total tau, abnormally phosphorylated tau and amyloid β 1-42 are strongly associated with Alzheimer's disease (AD). Apart from the pathologic hallmarks that these biomarkers represent, other processes such as inflammation and microglial activation are present in the brains of patients with AD. New biomarkers related to these processes could be valuable for the diagnosis and follow-up of AD patients and for the evaluation of inflammation-related pathologies.
Aim
The aim of this study was to evaluate the association of inflammatory CSF biomarkers with AD.
Methods
Twenty-five AD patients and 25 controls who had a pathological and normal CSF profile of the core AD biomarkers, respectively, were included in this study. CSF levels of chitotriosidase, YKL-40 (also known as chitinase-3-like protein 1) and monocyte chemoattractant protein-1 (MCP-1) were quantified and the levels compared between the groups.
Results
AD patients had increased CSF levels of chitotriosidase and YKL-40 (both approximately twice higher than in controls), while the levels of MCP-1 were similar in the AD and control groups.
Conclusion
The results indicate that chitotriosidase and YKL-40 may be helpful for the evaluation of cerebral inflammatory activity in AD patients.
doi:10.1159/000362164
PMCID: PMC4164083  PMID: 25254036
Alzheimer's disease; Cerebrospinal fluid; Biomarkers; Inflammation
15.  Diagnostic accuracy of CSF Ab42 and florbetapir PET for Alzheimer's disease 
Background
Reduced cerebrospinal fluid (CSF) β-amyloid42 (Aβ42) and increased florbetapir positron emission tomography (PET) uptake reflects brain Aβ accumulation. These biomarkers are correlated with each other and altered in Alzheimer's disease (AD), but no study has directly compared their diagnostic performance.
Methods
We examined healthy controls (CN, N = 169) versus AD dementia patients (N = 118), and stable (sMCI; no dementia, followed up for at least 2 years, N = 165) versus progressive MCI (pMCI; conversion to AD dementia, N = 59). All subjects had florbetapir PET (global and regional; temporal, frontal, parietal, and cingulate) and CSF Aβ42 measurements at baseline. We compared area under the curve (AUC), sensitivity, and specificity (testing a priori and optimized cutoffs). Clinical diagnosis was the reference standard.
Results
CSF Aβ42 and (global or regional) PET florbetapir did not differ in AUC (CN vs. AD, CSF 84.4%; global PET 86.9%; difference [95% confidence interval] −6.7 to 1.5). CSF Aβ42 and global PET florbetapir did not differ in sensitivity, but PET had greater specificity than CSF in most comparisons. Sixteen CN progressed to MCI and AD (six Aβ negative, seven Aβ positive, and three PET positive but CSF negative).
Interpretation
The overall diagnostic accuracies of CSF Aβ42 and PET florbetapir were similar, but PET had greater specificity. This was because some CN and sMCI subjects appear pathological using CSF but not using PET, suggesting that low CSF Aβ42 not always translates to cognitive decline or brain Aβ accumulation. Other factors, including costs and side effects, may also be considered when determining the optimal modality for different applications.
doi:10.1002/acn3.81
PMCID: PMC4184556  PMID: 25356425
16.  Impaired lipoprotein receptor-mediated peripheral binding of plasma Aβ is an early biomarker for mild cognitive impairment preceding Alzheimer’s disease 
Soluble circulating low density lipoprotein receptor-related protein-1 (sLRP) provides key plasma binding activity for Alzheimer’s disease (AD) amyloid β-peptide (Aβ). sLRP normally binds 70–90% of plasma Aβ preventing free Aβ access to the brain. In AD, Aβ binding to sLRP is compromised by increased levels of oxidized sLRP which does not bind Aβ. Here, we determined plasma oxidized sLRP and Aβ40/42 sLRP-bound, other proteins-bound and free plasma fractions, cerebrospinal fluid (CSF) tau/Aβ42 ratios and mini-mental state examination (MMSE) scores in patients with mild cognitive impairment (MCI) who progressed to AD (MCI-AD, n=14), AD (n=14) and neurologically healthy controls (n=14) recruited from the Göteborg MCI study. In MCI-AD patients prior to conversion to AD and AD patients, the respective increases in oxidized sLRP and free plasma Aβ40 and Aβ42 levels were 4.9 and 3.7-fold, 1.8 and 1.7-fold and 4.3 and 3.3-fold (P < 0.05, ANOVA with Tuckey post-hoc test). In MCI-AD and AD patients increases in oxidized sLRP and free plasma Aβ40 and Aβ42 correlated with increases in CSF tau/Aβ42 ratios and reductions in MMSE scores (P < 0.05, Pearson analysis). A heterogenous group of ‘stable’ MCI patients that was followed over 2–4 years (n=24) had normal CSF tau/Aβ42 ratios but increased oxidized sLRP levels (P < 0.05, Student’s t test). Data suggests that a deficient sLRP-Aβ binding might precede and correlate later in disease with an increase in the tau/Aβ42 CSF ratio and global cognitive decline in MCI individuals converting into AD, and therefore is an early biomarker for AD-type dementia.
doi:10.3233/JAD-2010-101248
PMCID: PMC4096563  PMID: 21157031
Mild cognitive impairment; Alzheimer’s disease; Aging; Biomarker; sLRP
17.  Genetic analysis implicates APOE, SNCA and suggests lysosomal dysfunction in the etiology of dementia with Lewy bodies 
Human Molecular Genetics  2014;23(23):6139-6146.
Clinical and neuropathological similarities between dementia with Lewy bodies (DLB), Parkinson's and Alzheimer's diseases (PD and AD, respectively) suggest that these disorders may share etiology. To test this hypothesis, we have performed an association study of 54 genomic regions, previously implicated in PD or AD, in a large cohort of DLB cases and controls. The cohort comprised 788 DLB cases and 2624 controls. To minimize the issue of potential misdiagnosis, we have also performed the analysis including only neuropathologically proven DLB cases (667 cases). The results show that the APOE is a strong genetic risk factor for DLB, confirming previous findings, and that the SNCA and SCARB2 loci are also associated after a study-wise Bonferroni correction, although these have a different association profile than the associations reported for the same loci in PD. We have previously shown that the p.N370S variant in GBA is associated with DLB, which, together with the findings at the SCARB2 locus, suggests a role for lysosomal dysfunction in this disease. These results indicate that DLB has a unique genetic risk profile when compared with the two most common neurodegenerative diseases and that the lysosome may play an important role in the etiology of this disorder. We make all these data available.
doi:10.1093/hmg/ddu334
PMCID: PMC4222357  PMID: 24973356
18.  Neurological Assessment and Its Relationship to CSF Biomarkers in Amateur Boxers 
PLoS ONE  2014;9(6):e99870.
Background
Mild traumatic brain injury (TBI) or concussion is common in many sports. Today, neuropsychological evaluation is recommended in the monitoring of a concussion and in return-to-play considerations. To investigate the sensitivity of neuropsychological assessment, we tested amateur boxers post bout and compared with controls. Further the relationship between neuropsychological test results and brain injury biomarkers in the cerebrospinal fluid (CSF) were investigated.
Method
Thirty amateur boxers on high elite level with a minimum of 45 bouts and 25 non-boxing matched controls were included. Memory tests (Rey Osterrieth Complex Figure, Listening Span, Digit Span, Controlled Word Association Test, and computerized testing of episodic memory), tests of processing speed and executive functions (Trail Making, Reaction Time, and Finger Tapping) were performed and related to previously published CSF biomarker results for the axonal injury marker neurofilament light (NFL).
Results
The neurological assessment showed no significant differences between boxers and controls, although elevated CSF NFL, as a sign of axonal injury, was detected in about 80% of the boxers 1–6 days post bout. The investigation of the relationship between neuropsychological evaluation and CSF NFL concentrations revealed that boxers with persisting NFL concentration elevation after at least 14 days resting time post bout, had a significantly poorer performance on Trail Making A (p = 0.041) and Simple Reaction Time (p = 0.042) compared to other boxers.
Conclusion
This is the first study showing traumatic axonal brain injury can be present without measureable cognitive impairment. The repetitive, subconcussive head trauma in amateur boxing causes axonal injury that can be detected with analysis of CSF NFL, but is not sufficient to produce impairment in memory tests, tests of processing speed, or executive functions. The association of prolonged CSF NFL increase in boxers with impairment of processing speed is an interesting observation, which needs to be verified in larger studies.
doi:10.1371/journal.pone.0099870
PMCID: PMC4062456  PMID: 24941067
19.  Cerebrospinal Fluid and Neuroimaging Biomarker Abnormalities Suggest Early Neurological Injury in a Subset of Individuals During Primary HIV Infection 
The Journal of Infectious Diseases  2013;207(11):1703-1712.
Background. Cerebrospinal fluid (CSF) and neuroimaging abnormalities demonstrate neuronal injury during chronic AIDS, but data on these biomarkers during primary human immunodeficiency virus (HIV) infection is limited.
Methods. We compared CSF concentrations of neurofilament light chain, t-tau, p-tau, amyloid precursor proteins, and amyloid-beta 42 in 92 subjects with primary HIV infection and 25 controls. We examined relationships with disease progression and neuroinflammation, neuropsychological testing, and proton-magnetic resonance spectroscopy (MRS)–based metabolites.
Results. Neurofilament light chain was elevated in primary HIV infection compared with controls (P = .0004) and correlated with CSF neopterin (r = 0.38; P = .0005), interferon gamma-induced protein 10 (r = 0.39; P = .002), white blood cells (r = 0.32; P = .004), protein (r = 0.59; P < .0001), and CSF/plasma albumin ratio (r = 0.60; P < .0001). Neurofilament light chain correlated with decreased N-acteylaspartate/creatine and glutamate/creatine in the anterior cingulate (r = −0.35, P = .02; r = −0.40, P = .009, respectively), frontal white matter (r = −0.43, P = .003; r = −0.30, P = .048, respectively), and parietal gray matter (r = −0.43, P = .003; r = −0.47, P = .001, respectively). Beta-amyloid was elevated in the primary infection group (P = .0005) and correlated with time infected (r = 0.34; P = .003). Neither marker correlated with neuropsychological abnormalities. T-tau and soluble amyloid precursor proteins did not differ between groups.
Conclusions. Elevated neurofilament light chain and its correlation with MRS-based metabolites suggest early neuronal injury in a subset of participants with primary HIV infection through mechanisms involving central nervous system inflammation.
doi:10.1093/infdis/jit088
PMCID: PMC3636785  PMID: 23460748
HIV/AIDS; primary HIV infection; biomarkers; neurological damage; neurofilament light chain; magnetic resonance spectroscopy
20.  Neuronal and Glia-Related Biomarkers in Cerebrospinal Fluid of Patients with Acute Ischemic Stroke 
BACKGROUND
Cerebral ischemia promotes morphological reactions of the neurons, astrocytes, oligodendrocytes, and microglia in experimental studies. Our aim was to examine the profile of CSF (cerebrospinal fluid) biomarkers and their relation to stroke severity and degree of white matter lesions (WML).
METHODS
A total of 20 patients (mean age 76 years) were included within 5–10 days after acute ischemic stroke (AIS) onset. Stroke severity was assessed using NIHSS (National Institute of Health stroke scale). The age-related white matter changes (ARWMC) scale was used to evaluate the extent of WML on CT-scans. The concentrations of specific CSF biomarkers were analyzed.
RESULTS
Patients with AIS had significantly higher levels of NFL (neurofilament, light), T-tau, myelin basic protein (MBP), YKL-40, and glial fibrillary acidic protein (GFAP) compared with controls; T-Tau, MBP, GFAP, and YKL-40 correlated with clinical stroke severity, whereas NFL correlated with severity of WML (tested by Mann–Whitney test).
CONCLUSIONS
Several CSF biomarkers increase in AIS, and they correlate to clinical stroke severity. However, only NFL was found to be a marker of degree of WML.
doi:10.4137/JCNSD.S13821
PMCID: PMC4039292  PMID: 24932109
stroke; cerebrospinal fluid; WML; neurodegeneration
21.  Levels of cerebrospinal fluid α-synuclein oligomers are increased in Parkinson’s disease with dementia and dementia with Lewy bodies compared to Alzheimer’s disease 
Introduction
The objective was to study whether α-synuclein oligomers are altered in the cerebrospinal fluid (CSF) of patients with dementia, including Parkinson disease with dementia (PDD), dementia with Lewy bodies (DLB), and Alzheimer disease (AD), compared with age-matched controls.
Methods
In total, 247 CSF samples were assessed in this study, including 71 patients with DLB, 30 patients with PDD, 48 patients with AD, and 98 healthy age-matched controls. Both total and oligomeric α-synuclein levels were evaluated by using well-established immunoassays.
Results
The levels of α-synuclein oligomers in the CSF were increased in patients with PDD compared with the controls (P < 0.05), but not in patients with DLB compared with controls. Interestingly, the levels of α-synuclein oligomers in the CSF were also significantly higher in patients with PDD (P < 0.01) and DLB (P < 0.05) compared with patients with AD. The levels of CSF α-synuclein oligomers and the ratio of oligomeric/total-α-synuclein could distinguish DLB or PDD patients from AD patients, with areas under the curves (AUCs) of 0.64 and 0.75, respectively. In addition, total-α-synuclein alone could distinguish DLB or PDD patients from AD patients, with an AUC of 0.80.
Conclusions
The levels of α-synuclein oligomers were increased in the CSF from α-synucleinopathy patients with dementia compared with AD cases.
doi:10.1186/alzrt255
PMCID: PMC4075410  PMID: 24987465
22.  CSF biomarker variability in the Alzheimer’s Association quality control program 
Background
The cerebrospinal fluid (CSF) biomarkers amyloid beta 1–42, total tau, and phosphorylated tau are used increasingly for Alzheimer’s disease (AD) research and patient management. However, there are large variations in biomarker measurements among and within laboratories.
Methods
Data from the first nine rounds of the Alzheimer’s Association quality control program was used to define the extent and sources of analytical variability. In each round, three CSF samples prepared at the Clinical Neurochemistry Laboratory (Mölndal, Sweden) were analyzed by single-analyte enzyme-linked immunosorbent assay (ELISA), a multiplexing xMAP assay, or an immunoassay with electrochemoluminescence detection.
Results
A total of 84 laboratories participated. Coefficients of variation (CVs) between laboratories were around 20% to 30%; within-run CVs, less than 5% to 10%; and longitudinal within-laboratory CVs, 5% to 19%. Interestingly, longitudinal within-laboratory CV differed between biomarkers at individual laboratories, suggesting that a component of it was assay dependent. Variability between kit lots and between laboratories both had a major influence on amyloid beta 1–42 measurements, but for total tau and phosphorylated tau, between-kit lot effects were much less than between-laboratory effects. Despite the measurement variability, the between-laboratory consistency in classification of samples (using prehoc-derived cutoffs for AD) was high (>90% in 15 of 18 samples for ELISA and in 12 of 18 samples for xMAP).
Conclusions
The overall variability remains too high to allow assignment of universal biomarker cutoff values for a specific intended use. Each laboratory must ensure longitudinal stability in its measurements and use internally qualified cutoff levels. Further standardization of laboratory procedures and improvement of kit performance will likely increase the usefulness of CSF AD biomarkers for researchers and clinicians.
doi:10.1016/j.jalz.2013.01.010
PMCID: PMC3707386  PMID: 23622690
Alzheimer’s disease; Cerebrospinal fluid; Biomarkers; External assurance; Quality control; Proficiency testing
23.  Modulation of β-amyloid by a single dose of GSK933776 in patients with mild Alzheimer’s disease: a phase I study 
Introduction
In this study, we evaluated the safety and pharmacodynamic effects of the Fc-inactivated anti-β-amyloid (anti-Aβ) monoclonal antibody GSK933776 in patients with mild Alzheimer’s disease and mild cognitive impairment. Aβ and tau levels were investigated in cerebrospinal fluid (CSF), and the relationship between Aβ levels and Aβ modulation in plasma was explored. The feasibility of a continuous sampling method using a lumbar catheter was assessed.
Methods
This trial was a phase I, open-label, uncontrolled, single-dose, exploratory experimental medicine study of intravenous GSK933776 at doses of 1 mg/kg, 3 mg/kg or 6 mg/kg (n = 6/group). The time course of plasma and CSF concentrations of GSK933776 and Aβ was assessed. Sample size was based on feasibility, and no formal statistical analyses were performed.
Results
Following administration of GSK933776 at doses of 1 mg/kg, 3 mg/kg and 6 mg/kg, there were decreases from baseline in CSF Aβ1–42 (from 0 to 12 hours) by 22.8 pg/ml (6.2%), 43.5 pg/ml (9.2%) and 60.5 pg/ml (12.5%), respectively. Plasma concentrations of total Aβ18–35 and Aβ4228–42 increased immediately after infusion and CSF tau concentration increased slightly, but did not significantly change, following administration of all doses of GSK933776. Pharmacokinetics confirmed the presence of GSK933776 in the CSF, which exhibited a dose–response relationship. One patient underwent minor surgery without sequelae following a ruptured lumbar catheter.
Conclusion
GSK933776 demonstrated pharmacological activity and target engagement in CSF and plasma, and the continuous sampling method via a catheter successfully assessed the Aβ changes following single-dose administration of GSK933776.
Trial registration
ClinicalTrials.gov Identifier: NCT01424436. Registered 4 August 2011
doi:10.1186/alzrt249
PMCID: PMC4055052  PMID: 24716469
24.  Cerebrospinal Fluid Biomarker and Brain Biopsy Findings in Idiopathic Normal Pressure Hydrocephalus 
PLoS ONE  2014;9(3):e91974.
Background
The significance of amyloid precursor protein (APP) and neuroinflammation in idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD) is unknown.
Objective
To investigate the role of soluble APP (sAPP) and amyloid beta (Aβ) isoforms, proinflammatory cytokines, and biomarkers of neuronal damage in the cerebrospinal fluid (CSF) in relation to brain biopsy Aβ and hyperphosphorylated tau (HPτ) findings.
Methods
The study population comprised 102 patients with possible NPH with cortical brain biopsies, ventricular and lumbar CSF samples, and DNA available. The final clinical diagnoses were: 53 iNPH (91% shunt-responders), 26 AD (10 mixed iNPH+AD), and 23 others. Biopsy samples were immunostained against Aβ and HPτ. CSF levels of AD-related biomarkers (Aβ42, p-tau, total tau), non-AD-related Aβ isoforms (Aβ38, Aβ40), sAPP isoforms (sAPPα, sAPPβ), proinflammatory cytokines (several interleukins (IL), interferon-gamma, monocyte chemoattractant protein-1, tumor necrosis factor-alpha) and biomarkers of neuronal damage (neurofilament light and myelin basic protein) were measured. All patients were genotyped for APOE.
Results
Lumbar CSF levels of sAPPα were lower (p<0.05) in patients with shunt-responsive iNPH compared to non-iNPH patients. sAPPβ showed a similar trend (p = 0.06). CSF sAPP isoform levels showed no association to Aβ or HPτ in the brain biopsy. Quantified Aβ load in the brain biopsy showed a negative correlation with CSF levels of Aβ42 in ventricular (r = −0.295, p = 0.003) and lumbar (r = −0.356, p = 0.01) samples, while the levels of Aβ38 and Aβ40 showed no correlation. CSF levels of proinflammatory cytokines and biomarkers of neuronal damage did not associate to the brain biopsy findings, diagnosis, or shunt response. Higher lumbar/ventricular CSF IL-8 ratios (p<0.001) were seen in lumbar samples collected after ventriculostomy compared to the samples collected before the procedure.
Conclusions
The role of sAPP isoforms in iNPH seems to be independent from the amyloid cascade. No neuroinflammatory background was observed in iNPH or AD.
doi:10.1371/journal.pone.0091974
PMCID: PMC3956805  PMID: 24638077
25.  Altered Concentrations of Amyloid Precursor Protein Metabolites in the Cerebrospinal Fluid of Patients with Bipolar Disorder 
Neuropsychopharmacology  2012;38(4):664-672.
Bipolar disorder is a psychiatric disorder characterized by recurrent episodes of mania/hypomania and depression. Progressive cognitive dysfunction such as impairments in executive function and verbal memory is common in euthymic bipolar patients. The cerebrospinal fluid has previously been used to study neurodegenerative processes in Alzheimer's disease, from which changes in three core biomarkers have emerged as indicative of degeneration: amyloid β, total tau, and hyperphosphorylated tau. Here, neurodegeneration in bipolar disorder was investigated by assessing the association between bipolar disorder and cerebrospinal fluid biomarkers for neurodegenerative processes. Cerebrospinal fluid was obtained from 139 bipolar disorder patients and 71 healthy controls. Concentrations of total and phosphorylated tau, amyloid β1-42, amyloid β38/β40/β42, and the soluble forms of amyloid precursor protein were measured in patients vs controls. The concentrations of the soluble forms of amyloid precursor protein were significantly lower in bipolar patients compared with controls. The amyloid β42/amyloid β38 and the amyloid β42/amyloid β40 ratios were higher in bipolar patients than controls. There were no discernible differences in the concentrations of total/phosphorylated tau, amyloid β1-42, or amyloid β38/β40/β42. The concentrations of the biomarkers within the bipolar patient group were further associated with different ongoing medical treatments and diagnostic subgroups. The findings suggest that the amyloid precursor protein metabolism is altered in bipolar disorder. The results may have implications for the understanding of the pathophysiology of bipolar disorder and for the development of treatment strategies. Importantly, there were no signs of an Alzheimer-like neurodegenerative process among bipolar patients.
doi:10.1038/npp.2012.231
PMCID: PMC3572463  PMID: 23212456
amyloid precursor protein; Tau protein; biomarkers; bipolar disorder; cerebrospinal fluid; Biological Psychiatry; Depression; Unipolar/Bipolar; Neurochemistry; Cognition; Bipolar Disorder; Biomarkers; amyloid precursor protein; Tau; cerebrospinal fluid

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