Neuronal DNA damage response-associated dysregulation of signalling pathways and cholesterol metabolism at the earliest stages of Alzheimer-type pathology.

AIMS: Oxidative damage and an associated DNA damage response (DDR) are evident in mild cognitive impairment and early Alzheimer's disease, suggesting that neuronal dysfunction resulting from oxidative DNA damage may account for some of the cognitive impairment not fully explained by Alzheimer-type pathology. METHODS: Frontal cortex (Braak stage 0-II) was obtained from the Medical Research Council's Cognitive Function and Ageing Study cohort. Neurones were isolated from eight cases (four high and four low DDR) by laser capture microdissection and changes in the transcriptome identified by microarray analysis. RESULTS: Two thousand three hundred seventy-eight genes were significantly differentially expressed (1690 up-regulated, 688 down-regulated, P < 0.001) in cases with a high neuronal DDR. Functional grouping identified dysregulation of cholesterol biosynthesis, insulin and Wnt signalling, and up-regulation of glycogen synthase kinase 3β. Candidate genes were validated by quantitative real-time polymerase chain reaction. Cerebrospinal fluid levels of 24(S)-hydroxycholesterol associated with neuronal DDR across all Braak stages (rs  = 0.30, P = 0.03). CONCLUSIONS: A persistent neuronal DDR may result in increased cholesterol biosynthesis, impaired insulin and Wnt signalling, and increased GSK3β, thereby contributing to neuronal dysfunction independent of Alzheimer-type pathology in the ageing brain

Neuronal DNA damage response-associated dysregulation of signalling pathways and cholesterol metabolism at the earliest stages of Alzheimer-type pathology.

AIMS: Oxidative damage and an associated DNA damage response (DDR) are evident in mild cognitive impairment and early Alzheimer's disease, suggesting that neuronal dysfunction resulting from oxidative DNA damage may account for some of the cognitive impairment not fully explained by Alzheimer-type pathology. METHODS: Frontal cortex (Braak stage 0-II) was obtained from the Medical Research Council's Cognitive Function and Ageing Study cohort. Neurones were isolated from eight cases (four high and four low DDR) by laser capture microdissection and changes in the transcriptome identified by microarray analysis. RESULTS: Two thousand three hundred seventy-eight genes were significantly differentially expressed (1690 up-regulated, 688 down-regulated, P < 0.001) in cases with a high neuronal DDR. Functional grouping identified dysregulation of cholesterol biosynthesis, insulin and Wnt signalling, and up-regulation of glycogen synthase kinase 3β. Candidate genes were validated by quantitative real-time polymerase chain reaction. Cerebrospinal fluid levels of 24(S)-hydroxycholesterol associated with neuronal DDR across all Braak stages (rs  = 0.30, P = 0.03). CONCLUSIONS: A persistent neuronal DDR may result in increased cholesterol biosynthesis, impaired insulin and Wnt signalling, and increased GSK3β, thereby contributing to neuronal dysfunction independent of Alzheimer-type pathology in the ageing brain

Population variation in glial fibrillary acidic protein levels in brain ageing: relationship to Alzheimer-type pathology and dementia

Background: the cellular pathology of astrocytes in brain ageing and their role in modulating the brain's response to neurodegenerative pathology remain incompletely understood. Methods: using quantitative ELISA, we have investigated glial fibrillary acidic protein (GFAP) expression in the population-based neuropathology cohort of the Medical Research Council Cognitive Function and Ageing Study to determine: (1) the population variation in the astroglial hypertrophic response, (2) its relationship to the presence of Alzheimer-type pathology, and (3) its association with cognition. Results: increasing GFAP was found with increasing Braak stage, levels increasing even at early stages. Within Braak stages, GFAP did not differ between demented and non-demented individuals, but there was greater variance in GFAP in the demented. Possession of ApoE 4 was associated with slightly increased GFAP levels (not significant) for given amyloid protein loads. Conclusion: in a population-based sample, increasing gliosis precedes development of Alzheimer lesions. Population variation in GFAP with varying Alzheimer lesion burdens suggests that they are not the only driver for astrogliosis. GFAP was not independently predictive of dementia, but the variation in astrocytic responses may be a factor modulating brain responses to neurodegenerative pathology<br/

Population variation in oxidative stress and astrocyte DNA damage in relation to Alzheimer-type pathology in the ageing brain

Increasing evidence suggests a role for oxidative damage to DNA in brain ageing and in neurodegenerative disorders, including Alzheimer's disease. Most studies have focussed on the reduced capacity for DNA repair by neurones, and have not taken into account the effect of oxidative stress on astrocytes, and their contribution to pathology

Neuropsychological tests for the diagnosis of Alzheimer’s disease dementia and other dementias: a generic protocol for cross-sectional and delayed-verification studies

This is the protocol for a review and there is no abstract. The objectives are as follows: To determine the cross-sectional diagnostic accuracy of [index test] at various thresholds for ADD and other dementias [target condition] in [target population].ORTo determine the accuracy of [index test] at various thresholds for diagnosing ADD and other dementias [target condition] in [target population] after a follow-up period (delayed-verification studies).To investigate the heterogeneity of test accuracy in the included studies.To highlight the quality and quantity of research evidence available on the effectiveness of the index test in the target population.To identify gaps in the evidence and determine where further research is required

Vascular Care in Patients with Alzheimer's Disease with Cerebrovascular Lesions-A Randomized Clinical Trial

OBJECTIVES: To investigate whether vascular care slows dementia progression in patients with Alzheimer's disease with cerebrovascular lesions on neuroimaging. DESIGN: Multicenter randomized controlled clinical trial with 2-year follow-up. SETTING: Neurological and geriatric outpatient clinics in 10 Dutch hospitals: three academic, five teaching, and two midsize community hospitals. PARTICIPANTS: One hundred thirty community-dwelling patients with mild dementia fulfilling clinical criteria for Alzheimer's disease with cerebrovascular lesions on neuroimaging. INTERVENTION: Patients randomized to vascular care were treated according to strict guidelines for hypercholesterolemia and hypertension. Acetylsalicylic acid, folic acid, and pyridoxine were prescribed. During visits every 3 months special attention was paid to smoking cessation, losing weight, and stimulating physical exercise. MEASUREMENTS: Primary outcome was disability, measured according to the Interview for Deterioration in Daily activities in Dementia (IDDD). Secondary outcomes were changes on the Mini-Mental State Examination (MMSE), the Revised Memory and Behavioural Problems Checklist (RMBPC), a composite measure of "poor outcome" (death, institutionalization, or severe clinical decline), and costs. RESULTS: Patients in the vascular and standard care condition declined equally on the IDDD (13.7 vs 11.0 points; difference 2.7, 95% confidence interval = -3.1-8.6). There was no treatment effect on the MMSE or RMBPC. There were no differences in institutionalization rate, "poor outcome" (41.4% vs 35.4%, P=.50), or costs. In the intervention group, there were three intracerebral hemorrhages and one gastrointestinal hemorrhage, versus none in the control group. CONCLUSION: Multicomponent vascular care, combining pharmacological and nonpharmacological interventions, does not slow decline in patients with Alzheimer's disease with cerebrovascular lesion