Importance: Substantial heterogeneity and uncertainty exist in the observed associations between alcohol consumption and dementia.
Objective: To assess the association between alcohol consumption and dementia and the roles of mild cognitive impairment (MCI) and apolipoprotein E ε4 (APOE E4) genotype in modifying this association.
Design, setting, and participants: This cohort study used data from the Ginkgo Evaluation of Memory Study, conducted from 2000 to 2008 among US community-dwelling participants. This study analyzed 3021 participants aged 72 years and older who were free of dementia. Data analysis was performed from 2017 to 2018.
Exposures: Self-reported alcohol consumption, drinking frequency, and quantity.
Main outcomes and measures: Using multivariable proportional hazards regression and linear mixed models, the risk of dementia and the rate of change over time in the Modified Mini-Mental State Examination were estimated.
Results: Among 3021 participants, the median (interquartile range) age was 78 (76-80) years; 1395 (46.2%) were female. During a median (interquartile range) follow-up of 6.0 (4.9-6.5) years, 512 cases of dementia occurred. For 7.1 to 14.0 drinks per week compared with less than 1.0 drink per week, the hazard ratios for dementia were 0.63 (95% CI, 0.38-1.06) among 2548 participants without MCI and 0.93 (95% CI, 0.47-1.84) among 473 participants with MCI. Among participants with MCI, the hazard ratio for dementia was 1.72 (95% CI, 0.87-3.40) for more than 14.0 drinks per week compared with less than 1.0 drink per week. The association of alcohol intake with dementia differed for participants with and without baseline MCI (P for interaction = .03). Among participants without MCI, daily low-quantity drinking was associated with lower dementia risk than infrequent higher-quantity drinking (hazard ratio, 0.45; 95% CI, 0.23-0.89; P = .02). Findings were consistent when stratified by sex, age, and APOE E4 genotype. Compared with drinking less than 1.0 drink per week, complete abstention (in participants without MCI) and the consumption of more than 14.0 drinks per week (in participants with MCI) were associated with lower Modified Mini-Mental State Examination scores (mean difference at follow-up compared with baseline, -0.46 point [95% CI, -0.87 to -0.04 point] and -3.51 points [95% CI, -5.75 to -1.27 points], respectively).
Conclusions and relevance: In this study, complete abstention and consuming more than 14.0 drinks per week (compared with drinking <1.0 drink per week) were associated with lower cognitive scores among participants aged 72 years and older. Particular caution is needed among individuals with MCI who continue to drink alcohol.