Alcohol’s “good-for-you, bad-for-you” reputation just got another “good-for-you” rating. According to a large cohort study, low-to-moderate alcohol consumption (10-14 drinks per week) by middle-aged and older adults is associated with better overall cognitive function.
“Low to moderate alcohol drinking was associated with protecting cognitive function as assessed by the total cognitive score and the scores of each of the 3 cognition domains tested (mental status, word recall, and vocabulary),” Ruiyuan Zhang, MD, MS, from the Department of Epidemiology and Biostatistics, University of Georgia College of Public Health, Athens, and colleagues wrote in JAMA Network Open. “We also found that compared with never drinkers, low to moderate drinkers had slower rates of cognitive decline across time for all cognition domains evaluated. The association was strongest for the vocabulary test.”
The emphasis of the study — a prospective cohort study of participants from the Health and Retirement Study (HRS) — was low to moderate drinking, which the researchers defined as fewer than 8 drinks a week for women and fewer than 15 drinks a week for men.
“Although the majority of drinkers in the HRS were low to moderate drinkers, 15.0% of white men (median 6; IQR, 2-12), 4.9% of white women (median, 3; IQR, 2-7), 15.7% of Black men (median, 6; IQR, 2-10), and 5.6% of Black women (median, 4; IQR, 2-6) had more than 14 drinks per week,” the study authors wrote, noting that public health campaigns still need to address excessive drinking among middle aged and older adults.
Moreover, the mechanism of action of how and why low-to-moderate alcohol consumption had these effects is not known, but Khang and colleagues do have some ideas.
“The main hypotheses focus on cerebrovascular and cardiovascular pathways and on brain-derived neurotrophic factor,” they wrote. “Several studies have found that low to moderate alcohol consumption is associated with better cardiovascular functions, fewer cardiac events, and longer survival compared with abstainers and heavy drinkers; thus, the decreased risk of cognitive impairment has been thought to be associated with alcohol consumption. However, a recent study found that alcohol consumption increases the risk of hypertension and stroke regardless of dose, which decreases the likelihood of this potential mechanism.”
This dichotomy, the good/evil of alcohol, led Khang and colleagues to opine that perhaps the cognitive benefit seen in their study “may be a balance of its beneficial and harmful effects on the cardiovascular system,” adding that with low-to-moderate drinking, the good effects may outweigh the bad.
Khang and colleagues included 19,887 participants from the HRS, which is a nationally representative sample of U.S. adults, followed for a mean of 9.1 years. The participants’ cognitive function was measured from 1996-2008 and had participated in at least 3 biennial surveys.
They researchers analyzed the trajectories and annual rates of change in three cognitive domains — mental status, word recall, and vocabulary. For the total cognitive score, they added the mental status and word recall scores.
“Participants were clustered into 2 cognitive function trajectories for each cognition measure assessed based on their scores at baseline and through at least 3 biennial surveys: a consistently low trajectory (representing low cognitive scores throughout the study period) and a consistently high trajectory (representing high cognitive scores throughout the study period),” the study authors wrote.
Khan and colleagues assessed alcohol consumption by surveying the participants with questions as to whether they drank any alcoholic beverages, what their average number of drinks was per week, and how many drinks they had consumed over the past 3 months. The participants were classified as never drinkers, former drinkers, and current drinkers.
Current drinkers were classified as low-to-moderate drinkers or heavy drinkers (8 or more drinks a week for women; 15 or more drinks a week for men).
They also analyzed covariates, including age, sex, race/ethnicity, education, marital status, tobacco smoking, and BMI. Smoking was assessed as never, former, or current smoker.
Most of the participants in the study were white, more than 60% were women, and the mean age of all the participants was around 62 years.
Among the results:
- “Low to moderate drinking was significantly associated with a consistently high cognitive function trajectory and a lower rate of cognitive decline.
- “Compared with never drinkers, low to moderate drinkers were less likely to have a consistently low trajectory for total cognitive function (odds ratio [OR], 0.66; 95% CI, 0.59-0.74), mental status (OR, 0.71; 95% CI, 0.63-0.81),word recall (OR, 0.74; 95% CI, 0.69-0.80), and vocabulary (OR, 0.64; 95% CI, 0.56-0.74) (all P < .001).
- “Low to moderate drinking was associated with decreased annual rates of total cognitive function decline (β coefficient, 0.04; 95% CI, 0.02-0.07; P = .002), mental status (β coefficient, 0.02; 95% CI, 0.01-0.03; P = .002), word recall (β coefficient, 0.02; 95% CI, 0.01-0.04; P = .01), and vocabulary (β coefficient, 0.01; 95% CI, 0.00-0.03; P = .08).
- “A significant racial/ethnic difference was observed for trajectories of mental status (P = .02 for interaction), in which low to moderate drinking was associated with lower odds of having a consistently low trajectory for white participants (OR, 0.65; 95% CI, 0.56-0.75) but not for Black participants (OR, 1.02; 95% CI, 0.74-1.39).
- “The dosage of alcohol consumed had a U-shaped association with all cognitive function domains for all participants, with an optimal dose of 10 to 14 drinks per week.”
Of note, the study authors do not specify the amount of alcohol consumed, i.e. number of ounces, nor do they specify type — wine, beer, or hard liquor.
Limitations of the study include that the participants self-reported their drinking habits and may have underestimated their consumption; few of the participants, particularly Black people and women, reported high weekly consumption; consumption changed over time, which might indicate that other factors influenced cognition; and the results might be confounded by health status. However, in commenting on the latter, Khang and colleagues pointed out that “77.2% of the participants had at least 1 chronic disease condition. Therefore, the association between alcohol drinking and cognitive function may be applicable both to healthy people and to those with a chronic disease.” Finally, the study authors noted that there were fewer people reporting high levels of weekly drinking, which suggests “the 95% CIs for the risk of having low cognitive function among these people were wide. Thus, the reliability of the estimates for this group could be low.”
Low-to-moderate alcohol drinking was associated with protecting cognitive function as assessed by the total cognitive score and the scores of each of the 3 cognition domains tested (mental status, word recall, and vocabulary).
Be aware that this study is a prospective cohort analysis that shows association, but not causation, and the data were self-reported by participants.
Candace Hoffmann, Managing Editor, BreakingMED™
The study was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health.
Zhang disclosed no relevant relationships.
Cat ID: 130
Topic ID: 82,130,282,404,494,730,130,33,361,192,255,925