Alcohol, dementia and cognitive decline in the elderly: a systematic review

Background: dementia and cognitive decline have been linked to cardiovascular risk. Alcohol has known negative effects in large quantities but may be protective for the cardiovascular system in smaller amounts. Effect of alcohol intake may be greater in the elderly and may impact on cognition. Methods: to evaluate the evidence for any relationship between incident cognitive decline or dementia in the elderly and alcohol consumption, a systematic review and meta-analyses were carried out. Criteria for inclusion were longitudinal studies of subjects aged 65, with primary outcomes of incident dementia/cognitive decline. Results: 23 studies were identified (20 epidemiological cohort, three retrospective matched case-control nested in a cohort). Meta-analyses suggest that small amounts of alcohol may be protective against dementia (random effects model, risk ratio [RR] 0.63; 95% CI 0.53-0.75) and Alzheimers disease (RR 0.57; 0.440-0.74) but not for vascular dementia (RR 0.82; 0.50-1.35) or cognitive decline (RR 0.89; 0.67-1.17) However, studies varied, with differing lengths of follow up, measurement of alcohol intake, inclusion of true abstainers and assessment of potential confounders. Conclusions: because of the heterogeneity in the data these findings should be interpreted with caution. However, there is some evidence to suggest that limited alcohol intake in earlier adult life may be protective against incident dementia later.