Grzegorz Agacinski

Abstract:

The understanding of how cerebrovascular disease (CVD) contributes to dementia is hampered by a lack of agreed and validated pathologic methods to accord weight to the contribution of different aspects of CVD to dementia. A previous study from the Oxford Project to Investigate Memory and Ageing (OPTIMA) validated a scheme for assessing the contribution of subcortical small vessel disease (SVD) toward dementia in the elderly by showing a significant inverse relationship between the severity of SVD and cognition in subjects without any other dementia pathology using this method. In the present paper, the method has been used to assess severity of SVD in 161 cases of neuropathologically confirmed Alzheimer disease. The results showed there was no relationship between the SVD score and cognitive scores acquired in the last 2 years of life. SVD scores were significantly related to age (P<0.0017) and were slightly but significantly higher in females than males (P<0.049). SVD scores were not related to blood pressure at entry to OPTIMA and were significantly lower when compared with the cohort of OPTIMA cases with only CVD (mean 5.06 ± 1.85 vs. 5.9 ± 2.67; P<0.0065). We conclude that when Alzheimer disease pathology is present in elderly subjects, it overwhelms the modest contribution that SVD makes to cognitive impairment.

Abstract:

The cannabinoid CB1 receptor has gained much attention as a potential pharmacotherapeutic target in various neurodegenerative diseases including Alzheimer's disease (AD). However, the relation of CB1 receptors to cognitive function in AD is at present unclear. In this study, postmortem brain tissues from a cohort of prospectively assessed, neuropathologically confirmed AD patients and aged controls were used to measure CB1 receptors by immunoblotting, and a subset of subjects also had [(3)H]SR141716A binding. Correlational analyses were then performed for the neurochemical and cognitive data. We found that CB1 receptor levels in were unchanged AD in the brain regions assessed (frontal cortex, anterior cingulate gyrus, hippocampus, caudate nucleus). Within the AD group, frontal cortical CB1 immunoreactivity correlated with cognitive scores assessed within a year of death. Our study suggests that CB1 receptors are intact in AD and may play a role in preserving cognitive function. Therefore, CB1 receptors should be further assessed as a potential therapeutic target in AD.

Abstract:

BACKGROUND: An increased rate of brain atrophy is often observed in older subjects, in particular those who suffer from cognitive decline. Homocysteine is a risk factor for brain atrophy, cognitive impairment and dementia. Plasma concentrations of homocysteine can be lowered by dietary administration of B vitamins. OBJECTIVE: To determine whether supplementation with B vitamins that lower levels of plasma total homocysteine can slow the rate of brain atrophy in subjects with mild cognitive impairment in a randomised controlled trial (VITACOG, ISRCTN 94410159). METHODS AND FINDINGS: Single-center, randomized, double-blind controlled trial of high-dose folic acid, vitamins B(6) and B(12) in 271 individuals (of 646 screened) over 70 y old with mild cognitive impairment. A subset (187) volunteered to have cranial MRI scans at the start and finish of the study. Participants were randomly assigned to two groups of equal size, one treated with folic acid (0.8 mg/d), vitamin B(12) (0.5 mg/d) and vitamin B(6) (20 mg/d), the other with placebo; treatment was for 24 months. The main outcome measure was the change in the rate of atrophy of the whole brain assessed by serial volumetric MRI scans. RESULTS: A total of 168 participants (85 in active treatment group; 83 receiving placebo) completed the MRI section of the trial. The mean rate of brain atrophy per year was 0.76% [95% CI, 0.63-0.90] in the active treatment group and 1.08% [0.94-1.22] in the placebo group (P =  0.001). The treatment response was related to baseline homocysteine levels: the rate of atrophy in participants with homocysteine >13 µmol/L was 53% lower in the active treatment group (P =  0.001). A greater rate of atrophy was associated with a lower final cognitive test scores. There was no difference in serious adverse events according to treatment category. CONCLUSIONS AND SIGNIFICANCE: The accelerated rate of brain atrophy in elderly with mild cognitive impairment can be slowed by treatment with homocysteine-lowering B vitamins. Sixteen percent of those over 70 y old have mild cognitive impairment and half of these develop Alzheimer's disease. Since accelerated brain atrophy is a characteristic of subjects with mild cognitive impairment who convert to Alzheimer's disease, trials are needed to see if the same treatment will delay the development of Alzheimer's disease. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN94410159.