Abstract and Introduction
Abstract
The authors evaluated the association of low-to-moderate alcohol consumption with risk of cognitive decline in a census-based cohort study of men and women aged ≥55 years conducted in Zaragoza, Spain (1994–1999). Participants free of dementia at baseline (N = 3,888) were examined after 2.5 and 4.5 years of follow-up. Information on alcohol intake was collected with the EURODEM Risk Factors Questionnaire and the History and Aetiology Schedule. The study endpoint was severe cognitive decline, defined as loss of ≥1 point/year on the Mini-Mental State Examination or a diagnosis of incident dementia (Diagnostic and Statistical Manual of Mental Disorders: DSM-IV, Text Revision criteria). Compared with those for abstainers, the multivariate-adjusted odds ratios for severe cognitive decline for male drinkers of <12 g alcohol/day, drinkers of 12–24 g alcohol/day, and former drinkers were 0.61 (95% confidence interval (CI): 0.31, 1.20), 1.19 (95% CI: 0.61, 2.32), and 1.03 (95% CI: 0.59, 1.82), respectively. The corresponding odds ratios for women were 0.88 (95% CI: 0.45, 1.72), 2.38 (95% CI: 0.98, 5.77), and 1.03 (95% CI: 0.48, 2.23). This study did not support the hypothesis that low-to-moderate alcohol consumption prevents cognitive decline. The inverse association between low-to-moderate alcohol intake and cognitive decline observed in other studies may have been due to inclusion of former drinkers in the abstainers reference category.
Introduction
Heavy alcohol consumption impairs cognitive performance and is related to clinical dementia. However, low-to-moderate alcohol intake may protect against dementia and cognitive deterioration. A number of biologic mechanisms have been proposed to explain this potential beneficial effect of moderate alcohol consumption on the brain, including the antioxidant properties of wine flavonoids and alcohol-related prevention of ischemia or stroke. A recent systematic review also suggested that limited alcohol intake in early adult life may protect against incident dementia, although these findings were difficult to interpret because of high between-study heterogeneity.
The protective effect of moderate alcohol consumption is still controversial, however, and some studies have reported harmful effects of moderate alcohol intake. Indeed, the evidence for a protective effect may have been overestimated because of inclusion of former drinkers in the nondrinkers comparator group in most studies. For example, Ganguli et al. reported that mild-to-moderate drinking, compared with no drinking, was associated with a lower average decline in cognitive domains. Much of this difference was explained by lower declines among current drinkers when compared with former drinkers, whereas lifelong abstainers did not differ from current moderate drinkers. Other potential methodological issues in studies of moderate alcohol intake and cognitive decline include lack of standardization in the definition of alcohol drinking categories, problems related to missing observations and dropouts in longitudinal data, and the possibility of publication bias.
In this article, we report the association between alcohol intake and risk of incident cognitive decline in the ZARADEMP Project, a prospective, population-based study of adults 55 years of age or older living in Zaragoza, Spain. The ZARADEMP Project used carefully standardized methods to collect alcohol intake and cognitive function data over 4.5 years of follow-up.