Serum neurofilament light chain in behavioral variant frontotemporal dementia

Objective To determine the association of serum neurofilament light chain (NfL) with functional deterioration and brain atrophy during follow-up of patients with behavioral variant frontotemporal dementia (bvFTD). Methods Blood NfL levels from 74 patients with bvFTD, 26 with Alzheimer disease (AD), 17 with mild cognitive impairment (MCI), and 15 healthy controls (Con) at baseline and follow-up were determined and analyzed for the diagnostic potential in relation to functional assessment (Clinical Dementia Rating Scale Sum of Boxes [CDR-SOB], frontotemporal lobar degeneration-related CDR-SOB, Mini-Mental State Examination [MMSE]) and brain volumetry. Results At baseline, serum NfL level correlated with CSFNfL (bvFTD r = 0.706, p < 0.0001;AD/MCI r = 0.666, p = 0.0003). Highest serum levels were observed in bvFTD (p < 0 0.0001 vs Con and MCI, p = 0.0078 vs AD, respectively). Discrimination of bvFTD from Con/MCI/AD was possible with 91%/74%/74% sensitivity and 79%/74%/58% specificity. At follow-up, serum NfL increased in bvFTD and AD (p = 0.0039 and p = 0.0006, respectively). At baseline and follow-up, NfL correlated with functional scores of patients with bvFTD (e.g., CDR-SOB [baseline] r = 0.4157, p = 0.0006;[follow-up] r = 0.5629, p < 0.0001) and with atrophy in the gray and white matter of many brain regions including frontal and subcortical areas (e.g., frontal lobe: r = -0.5857, p < 0.0001;95% confidence interval -0.7415 to -0.3701). For patients with AD/MCI, NfL correlated with the functional performance as well (e.g., CDR-SOB [baseline] r = 0.6624, p < 0.0001;[follow-up] r = 0.5659, p = 0.0003) but not with regional brain volumes. Conclusions As serum NfL correlates with functional impairment and brain atrophy in bvFTD at different disease stages, we propose it as marker of disease severity, paving the way for its future use as outcome measure for clinical trials. Classification of evidence This study provides Class III evidence that for patients with cognitive problems, serum NfL concentration discriminates bvFTD from other forms of dementia

Effects of Short-Term Exercise Interventions on Behavioral and Psychological Symptoms in Patients with Dementia: A Systematic Review

Observational and interventional studies indicate a direct link between the patients' physical activity and the extent of behavioral and psychological symptoms of dementia (BPSD). At present, there are no evidence-based recommendations for physical exercise in the acute dementia care settings. Hence, this systematic review investigates the effects of short-term exercise trials on BPSD. Trials with a length up to three months investigating the effects of structured exercise interventions on BPSD in acute dementia care settings were included. Five trials, referring to a total of N=206 patients, met the inclusion criteria. The trial durations ranged from three up to twelve weeks. All trials conducted three sessions per week of 30 to 45 minutes. Three trials reported significant reductions of BPSD and differences in comparison to the pre-test and control groups. Out of the three trials investigating the effects of exercise interventions on depressive symptoms, one reported significant reduction and two reported no differences in pre-post analysis. Exercise represents a potentially worthwhile approach for the treatment of patients suffering from BPSD. Given the scarcity of available studies, more randomized controlled short-term exercise trials in acute dementia care settings are needed to define appropriate exercise recommendations for clinicians treating these patients

Visual Versus Fully Automated Analyses of F-18-FDG and Amyloid PET for Prediction of Dementia Due to Alzheimer Disease in Mild Cognitive Impairment

Biomarkers of Alzheimer disease (AD) can be imaged in vivo and can be used for diagnostic and prognostic purposes in people with cognitive decline and dementia. Indicators of amyloid deposition such as C-11-Pittsburgh compound B (C-11-PiB) PET are primarily used to identify or rule out brain diseases that are associated with amyloid pathology but have also been deployed to forecast the clinical course. Indicators of neuronal metabolism including F-18-FDG PET demonstrate the localization and severity of neuronal dysfunction and are valuable for differential diagnosis and for predicting the progression from mild cognitive impairment (MCI) to dementia. It is a matter of debate whether to analyze these images visually or using automated techniques. Therefore, we compared the usefulness of both imaging methods and both analyzing strategies to predict dementia due to AD. Methods: In MCI participants, a baseline examination, including clinical and imaging assessments, and a clinical follow-up examination after a planned interval of 24 mo were performed. Results: Of 28 MCI patients, 9 developed dementia due to AD, 2 developed frontotemporal dementia, and 1 developed moderate dementia of unknown etiology. The positive and negative predictive values and the accuracy of visual and fully automated analyses of C-11-PiB for the prediction of progression to dementia due to AD were 0.50, 1.00, and 0.68, respectively, for the visual and 0.53, 1.00, and 0.71, respectively, for the automated analyses. Positive predictive value, negative predictive value, and accuracy of fully automated analyses of F-18-FDG PET were 0.37, 0.78, and 0.50, respectively. Results of visual analyses were highly variable between raters but were superior to automated analyses. Conclusion: Both F-18-FDG and C-11-PiB imaging appear to be of limited use for predicting the progression from MCI to dementia due to AD in short-term follow-up, irrespective of the strategy of analysis. On the other hand, amyloid PET is extremely useful to rule out underlying AD. The findings of the present study favor a fully automated method of analysis for C-11-PiB assessments and a visual analysis by experts for F-18-FDG assessments

LRP-1 polymorphism is associated with global and regional amyloid load in Alzheimer's disease in humans in-vivo

Objective: Impaired amyloid clearance has been proposed to contribute to beta-amyloid deposition in sporadic late-onset Alzheimer's disease (AD). Low density lipoprotein receptor-related protein 1 (LRP-1) is involved in the active outward transport of beta-amyloid across the blood-brain barrier (BBB). The C667T polymorphism (rs1799986) of the LRP-1 gene has been inconsistently associated with AD in genetic studies. We aimed to elucidate the association of this polymorphism with in-vivo brain amyloid load of AD patients using amyloid PET with [C-11] PiB. Materials and methods: 72 patients with very mild to moderate AD were examined with amyloid PET and C667T polymorphism was obtained using TaqMan PCR assays. The association of C667T polymorphism with global and regional amyloid load was calculated using linear regression and voxel based analysis, respectively. The effect of the previously identified modulator of amyloid uptake, the apolipoprotein E genotype, on this association was also determined. Results: The regression analysis between amyloid load and C667T polymorphism was statistically significant (p = 0.046, beta = 0.236). In an additional analysis ApoE genotype and gender were identified to explain further variability of amyloid load. Voxel based analysis revealed a significant (p < 0.05) association between C667T polymorphism and amyloid uptake in the temporo-parietal cortex bilaterally. ApoE did not interact significantly with the LRP-1 polymorphism. Discussion: In conclusion, C667T polymorphism of LRP-1 is moderately but significantly associated with global and regional amyloid deposition in AD. The relationship appears to be independent of the ApoE genotype. This finding is compatible with the hypothesis that impaired amyloid clearance contributes to amyloid deposition in late-onset sporadic AD. (C) 2014 The Authors. Published by Elsevier Inc

Examination of the Current Top Candidate Genes for AD in a Genome-Wide Association Study

With the advent of technologies that allow simultaneous genotyping of thousands of singlenucleotide polymorphisms (SNPs) across the genome, the genetic contributions to complex diseases can be explored at an unprecedented detail. This study is among the first to apply the genome-wide association study (GWAS) approach to Alzheimer disease (AD). We present our GWAS results from the German population for genes included in the ‘Top Results’ list on the AlzGene database website. In addition to the apolipoprotein E locus, we identified nominally significant association signals in six of the ten genes investigated, albeit predominantly for SNPs other than those already published as being disease associated. Further, all of the four AD genes previously identified through GWAS also showed nominally significant association signals in our data. The results of our comparative study reinforce the necessity for replication and validation, not only of GWAS but also of candidate gene case–control studies, in different populations. Furthermore, cross-platform comparison of genotyping results can also identify new association signals. Finally, our data confirm that GWAS, regardless of the platform, are valuable for the identification of genetic variants associated with A

Herpes simplex virus alters Alzheimer's disease biomarkers - A hypothesis paper

Introduction: Human herpes simplex virus 1 (HSV1) is discussed to induce amyloid-beta (A beta) accumulation and neurofibrillary tangles of hyperphosphorylated tau (pTau) in Alzheimer's disease (AD) in cell culture and animal models. A beta appears to be virostatic. We investigated the association between intrathecal antibodies against HSV or cytomegalovirus (CMV) and cerebrospinal fluid (CSF) AD biomarkers. Methods: beta(42)/A beta(40) ratio, pTau, and tTau were measured in CSF of 117 patients with early AD positive for amyloid pathology (A+) and 30 healthy controls (A-). CSF-to-serum anti-HSV1/2-IgG antibody indices (AI-IgG(HSV1/2)) and CMV (AI-IgG(CMV)) were determined by enzyme-linked immunosorbent assay (ELISA). Results: Exclusively in HSV1-seropositive AD, pTau was positively and significantly predicted by AI-IgG(HSV1/2) and negatively by the A beta(42)/A beta(40) ratio in both univariate and multivariate regression analyses. Furthermore, a significant and negative interaction between the AI-IgG(HSV1/2) and A beta(42)/A beta(40) ratio on pTau was found.Discussion: The results support the hypothesis that HSV infection contributes to AD

Within-patient correspondence of amyloid-beta and intrinsic network connectivity in Alzheimer's disease

There is striking overlap between the spatial distribution of amyloid-beta pathology in patients with Alzheimer's disease and the spatial distribution of high intrinsic functional connectivity in healthy persons. This overlap suggests a mechanistic link between amyloid-beta and intrinsic connectivity, and indeed there is evidence in patients for the detrimental effects of amyloid-beta plaque accumulation on intrinsic connectivity in areas of high connectivity in heteromodal hubs, and particularly in the default mode network. However, the observed spatial extent of amyloid-beta exceeds these tightly circumscribed areas, suggesting that previous studies may have underestimated the negative impact of amyloid-beta on intrinsic connectivity. We hypothesized that the known positive baseline correlation between patterns of amyloid-beta and intrinsic connectivity may mask the larger extent of the negative effects of amyloid-beta on connectivity. Crucially, a test of this hypothesis requires the within-patient comparison of intrinsic connectivity and amyloid-beta distributions. Here we compared spatial patterns of amyloid-beta-plaques (measured by Pittsburgh compound B positron emission tomography) and intrinsic functional connectivity (measured by resting-state functional magnetic resonance imaging) in patients with prodromal Alzheimer's disease via spatial correlations in intrinsic networks covering fronto-parietal heteromodal cortices. At the global network level, we found that amyloid-beta and intrinsic connectivity patterns were positively correlated in the default mode and several fronto-parietal attention networks, confirming that amyloid-beta aggregates in areas of high intrinsic connectivity on a within-network basis. Further, we saw an internetwork gradient of the magnitude of correlation that depended on network plaque-load. After accounting for this globally positive correlation, local amyloid-beta-plaque concentration in regions of high connectivity co-varied negatively with intrinsic connectivity, indicating that amyloid-beta pathology adversely reduces connectivity anywhere in an affected network as a function of local amyloid-beta-plaque concentration. The local negative association between amyloid-beta and intrinsic connectivity was much more pronounced than conventional group comparisons of intrinsic connectivity would suggest. Our findings indicate that the negative impact of amyloid-beta on intrinsic connectivity in heteromodal networks is underestimated by conventional analyses. Moreover, our results provide first within-patient evidence for correspondent patterns of amyloid-beta and intrinsic connectivity, with the distribution of amyloid-beta pathology following functional connectivity gradients within and across intrinsic networks