Cerebrospinal fluid alpha-synuclein does not discriminate between dementia disorders.

Alpha-synuclein is the major constituent of Lewy bodies found in neurons in dementia with Lewy bodies (DLB) and might be of diagnostic value as a biomarker for DLB. We hypothesized that, as a consequence of increased accumulation of alpha-synuclein intraneuronally in DLB, the levels of alpha-synuclein in cerebrospinal fluid (CSF) of DLB patients would be lower than in other dementias. Our objective was to investigate the CSF levels of alpha-synuclein in several dementia disorders compared to control levels and to investigate the diagnostic value of CSF alpha-synuclein as a marker to discriminate between DLB and other types of dementia. We analyzed the levels of alpha-synuclein in CSF of 40 DLB patients, 131 patients with Alzheimer's disease, 28 patients with vascular dementia, and 39 patients with frontotemporal dementia. We did not find any significant differences in CSF alpha-synuclein levels between DLB patients and patients with Alzheimer's disease, vascular dementia or frontotemporal dementia. We conclude that in clinically diagnosed patients, alpha-synuclein does not appear to be a useful biomarker for the differentiation between DLB and other types of dementia.

Small heat shock proteins Hsp27 or alphaB-crystallin and the protein components of neurofibrillary tangles: tau and neurofilaments.

The heat-shock proteins (HSPs) Hsp27 and alphaB-crystallin are up-regulated in Alzheimer's disease (AD), but the extent of this and the consequences are still largely unknown. The HSPs are involved in protein degradation and protection against protein aggregation, and they interact with several cytoskeletal components such as microtubules (MT) and neurofilaments (NF). AD pathology includes aggregated proteins (tau, NF), decreased protein degradation, and cytoskeletal disruption. It is thus of interest to investigate more closely the possible roles of the HSPs in AD pathology. The expressions of Hsp27 and alphaB-crystallin in AD brain samples were significantly increased (by approximately 20% and approximately 30%, respectively) and correlated significantly with phosphorylated tau and NF proteins. To investigate the consequences of increased HSP levels on tau and NF regulation, N2a cells were transfected with Hsp27 or alphaB-crystallin constructs, and overexpression of the HSPs was confirmed in the cells. Increased tau phosphorylation at the Ser262 site in the N2a cells was regulated by Hsp27 overexpression (possibly through p70S6k), whereas the overexpression of alphaB-crystallin resulted in decreased levels of phosphorylated tau, NF, and GSK-3beta. It was also shown that overexpression of HSPs causes an increase in the percentage of cells present in the G(1) phase. The results presented suggest that a cellular defense against dysregulated proteins, in the form of Hsp27 and alphaB-crystallin, might contribute to the cell cycle reentry seen in AD cells. Furthermore, Hsp27 might also be involved in AD pathology by aggravating MT disruption by tau phosphorylation.

Vagus nerve stimulation in patients with Alzheimer's disease: Additional follow-up results of a pilot study through 1 year.

BACKGROUND: Cognitive-enhancing effects of vagus nerve stimulation (VNS) have been reported during 6 months of treatment in a pilot study of patients with Alzheimer's disease (AD). Data through 1 year of VNS (collected from June 2000 to September 2003) are now reported. METHOD: All patients (N = 17) met the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for probable AD. Responder rates for the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and Mini-Mental State Examination (MMSE) were measured as improvement or absence of decline from baseline. Global change, depressive symptoms, and quality of life were also assessed. Cerebrospinal fluid (CSF) levels for total tau, tau phosphorylated at Thr181 (phosphotau), and Abeta42 were measured by standardized enzyme-linked immunosorbent assay (ELISA). RESULTS: VNS was well tolerated. After 1 year, 7 (41.2%) of 17 patients and 12 (70.6%) of 17 patients improved or did not decline from baseline on the ADAS-cog and MMSE, respectively. Twelve of 17 patients were rated as having no change or some improvement from baseline on the Clinician Interview-Based Impression of Change (CIBIC+). No significant decline in mood, behavior, or quality of life occurred during 1 year of treatment. The median change in CSF tau at 1 year was a reduction of 4.8% (p = .057), with a 5.0% increase in phosphotau (p = .040; N = 14). CONCLUSION: The results of this study support long-term tolerability of VNS among patients with AD and warrant further investigation.

Zinc induces neurofilament phosphorylation independent of p70 S6 kinase in N2a cells.

Hyperphosphorylated neurofilaments are a part of neurofibrillary tangles in Alzheimer's disease brains. Zinc has been shown to be increased in the brain areas heavily affected by Alzheimer pathologies. Zinc could induce tau hyperphosphorylation in SH-SY5Y and N2a cells, and tau phosphorylation may be mediated by p70 S6 kinase activation. Many of the tau kinases can also phosphorylate neurofilaments, and in this study we wanted to see whether neurofilament phosphorylation is regulated by p70 S6 kinase in N2a cells. We found that zinc induces rapamycin-dependent p70 S6 kinase phosphorylation at Thr421/Ser424 and Thr389, and rapamycin-independent phosphorylation of neurofilaments at the SMI34 epitope. Although zinc could induce cell proliferation and cell growth, and increased phosphorylation of neurofilaments, only cell growth appeared to be related to p7056kinase activation.

Cognition-enhancing effect of vagus nerve stimulation in patients with Alzheimer's disease: a pilot study.

BACKGROUND: Vagus nerve stimulation (VNS) is an established treatment method for therapy-refractory epilepsy and, in Europe, for treatment-resistant depression also. Clinical and experimental investigations have also shown positive effects of VNS on cognition in epilepsy and depression. The purpose of the present pilot study was to investigate the effect of VNS on cognition in patients with Alzheimer's disease. METHOD: All the included patients (N = 10) met the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association criteria for the diagnosis of Alzheimer's disease. Before the implantation of the vagus stimulator (NeuroCybernetic Prosthesis), the patients underwent neuropsychological tests (e.g., Alzheimer's Disease Assessment Scale-cognitive subscale [ADAS-cog] and Mini-Mental State Examination [MMSE]), computerized tomography of the brain, medical/neurologic and psychological examinations (status evaluation), and lumbar puncture with investigation of the cerebrospinal fluid. The presence of depressive symptoms was rated using the Montgomery-Asberg Depression Rating Scale. The VNS was initiated 2 weeks after the implantation, and the patients were followed up with regular investigations and tests over 6 months. Response was defined as improvement or absence of impairment in ADAS-cog and MMSE scores after 3 and 6 months. RESULTS: After 3 months of treatment, 7 of 10 patients were responders according to the ADAS-cog (median improvement of 3.0 points), and 9 of 10 patients were responders according to the MMSE (median improvement of 1.5 points). After 6 months of treatment, 7 patients were responders on the ADAS-cog (median improvement of 2.5 points), and 7 patients were responders on the MMSE (median improvement of 2.5 points). VNS was well tolerated, and its side effects were mild and transient. CONCLUSION: The results of this open-label pilot study suggest a positive effect of VNS on cognition in patients with Alzheimer's disease. Further studies are warranted.

Alzheimer biomarkers and clinical Alzheimer disease were not associated with increased cerebrovascular disease in a memory clinic population.

OBJECTIVE: Preclinical and post-mortem studies suggest that Alzheimer disease (AD) causes cerebrovascular dysfunction, and therefore may enhance susceptibility to cerebrovascular disease (CVD). The objective of this study was to investigate this association in a memory clinic population. METHODS: The AD biomarkers CSF amyloid ß42, amyloid ß40 and APOE-ε4 status have all been linked to increased CVD risk in AD, and therefore the first aim of this study was to analyze the association between these biomarkers and CVD. In 92 memory clinic patients the cross-sectional association between AD biomarkersand the severity of CVD was investigated with linear regression analysis. Additionally, we studied whether AD biomarkers modified the relation between vascular risk factors and CVD. CVD was assessed on MRI through a visual rating scale.Analyses were adjusted for age. The second aim of this study was to investigate the association between clinical AD and CVD, where 'clinical AD' was defined as follows: impairment in episodic memory, hippocampal atrophy and an aberrant concentration of cerebrospinal fluid (CSF) biomarkers. 47 of the 92 patients had AD. RESULTS: No association between CSF amyloid ß42, amyloid ß40 or APOE-ε4 status and CVD severity was found, nor did these AD biomarkers modify the relation between vascular risk factors and CVD. Clinical AD was not associated with CVD severity (p=0.83). Patients with more vascular risk factors had more CVD, but this relationship was not convincingly modified by AD (p=0.06). CONCLUSIONS: In this memory clinic population, CVD in patients with AD was related to vascular risk factors and age, comparable to patients without AD. Therefore, in our study, the preclinical and post-mortem evidence that AD would predispose to CVD could not be translated clinically. Further work, including replication of this work in a different and larger sample, is warranted.

Hourly variability of cerebrospinal fluid biomarkers in Alzheimer's disease subjects and healthy older volunteers.

Large hour-to-hour variability has previously been demonstrated in the cerebrospinal fluid (CSF) concentrations of Alzheimer's disease (AD) biomarkers amyloid ß(42) (Aß(42)) and Aß(40) in healthy younger subjects. We investigated the within-subject variability over 36 hours in CSF Aß and tau proteins, in older subjects and AD patients. Six patients with mild stage AD (59-85 years, Mini Mental State Examination (MMSE) 16-26) and 6 healthy older volunteers (64-77 years) received an intrathecal catheter from which, during 36 hours, each hour 6 mL of CSF was drawn. Concentrations of Aß(42), Aß(40), total tau, and phosphorylated tau were determined and the variability was analyzed. Within-subject variability within 3-hour periods was assessed as the coefficient of variation, which was comparable for these 4 biomarkers in controls (4.2%-4.6%) and AD (3.1%-5.8%). Variability over 12 hour periods was 5.3% to 9.5%. These findings suggest that CSF biomarker variability is relatively low in healthy older controls and AD patients. Furthermore, continuous sampling of CSF proved to be a useful and robust method, which may also be used to investigate AD pathogenesis and to evaluate pharmacotherapeutic interventions.

Cerebrospinal Fluid Biomarkers in Diagnosing Alzheimer's Disease in Clinical Practice: An Illustration with 3 Case Reports.

Analysis of the brain specific biomarkers amyloid beta(42) (Abeta(42)) and total tau (t-tau) protein in cerebrospinal fluid (CSF) has a sensitivity and specificity of more than 85% for differentiating Alzheimer's Disease (AD) from non-demented controls. International guidelines are contradictory in their advice on the use of CSF biomarkers in AD diagnostics, resulting in a lack of consistency in clinical practice. We present three case reports that illustrate clinical practice according to the Dutch and European guidelines and portray the value of CSF biomarker analysis as an add-on diagnostic to the standard diagnostic workup for AD.

Assessments of the accumulation severities of amyloid beta-protein and hyperphosphorylated tau in the medial temporal cortex of control and Alzheimer's brains.

Alzheimer's disease (AD) is characterized neuropathologically by neuritic plaques (NPs), and neurofibrillary tangles (NFTs). So far, the following key issues are not yet answered to the disease: (1) the accumulation degrees of three Abeta variants, and tau phosphorylation epitopes in AD as compared to control; (2) the correlation degrees of levels of three Abeta variants with different tau phosphorylation epitopes; (3) the correlation degrees of levels of three Abeta variants and different tau phosphorylation epitopes with Braak and CERAD staging systems. To address these issues, levels of Abeta40, Abeta42, and Abeta43, and phosphorylated tau were assessed by dot blots in homogenates of the medial temporal cortex from AD and control brains in the present study. These data implied different roles of tau phosphorylation epitopes in formation of NFTs, and in this process, Abeta might play a key role. Assessments of levels of these abnormal proteins by dot blots may serve as a useful complement to the morphological evaluations in diagnosis of AD.