Review of: Zhang R et al, JAMA Netw Open 2020;3(6):e207922

Is alcohol good or bad for cognition? The evidence is mixed. A new study brings additional clarity to this question by including a diverse patient population and by using longitudinal cognitive measurements of the subjects as opposed to cross-sectional evaluations at one time point.

In an NIH-funded investigation, 19,887 participants from the Health and Retirement Study, a nationally representative cohort of middle-aged and older US adults, had at least 4 cognitive measurements performed between 1996 and 2008. Total word recall, mental status, and vocabulary were assessed. Use of alcohol over the past 3 months was reviewed during surveys. Women who reported less than 8 drinks per week and men who reported less than 15 drinks per week were considered low to moderate drinkers. 7,057 subjects (35.4%) met these low to moderate drinking criteria. The mean age of the subjects was 61.8 years. 60.1% were women and 85.2% were Caucasian.

The analysis showed that low to moderate drinkers were less likely to have low cognitive function scores than never-drinkers (odds ratio 0.66; 95% confidence interval [CI] 0.59–0.74), even after adjusting for age, sex, race/ethnicity, years of education, marital status, and other substance use. Low to moderate drinkers also had statistically less cognitive decline with an effect size of 0.04 (95% CI 0.01–0.04; p = 0.02). The researchers found that there was a U-shaped association between drinking and cognitive decline—meaning very low and very high intake were linked to poorer cognition scores, but moderate intake was associated with better scores. The optimal alcohol dosage associated with better cognitive function was 10–14 drinks per week for all participants. Interestingly, low to moderate drinking was beneficial for white participants, but not for Black participants. No gender-related differences were found between alcohol drinking and cognitive functions.

CATR’s Take
This study suggests that low to moderate alcohol use in middle-aged and older adults may be associated with better total cognitive function and slower rates of cognitive decline, thought to be due to alcohol’s impact on cerebrovascular and cardiovascular pathways. These associations are stronger for white participants than Black participants. While low to moderate alcohol use may promote cognition in certain populations, we should remain cautious about endorsing alcohol use to all middle-aged and older patients, especially those with preexisting psychiatric or medical conditions.