Men who drink more than an average of about 2.5 standard units of alcohol a day had 6 years faster cognitive decline compared with light to moderate alcohol drinkers, researchers found.
To examine the association between alcohol consumption in midlife and subsequent cognitive decline, British researchers reviewed data from more than 5,000 men and nearly 2,100 women from the Whitehall II study, an ongoing study of British civil servants.
Alcoholic drinks were converted to grams of alcohol consumed per week and divided by 7 to an average daily alcohol consumption measured in grams per day. (One standard drink equals 13.6 grams of absolute alcohol, or about 2.5 drinks per day.) Alcohol consumption was assessed 3 times in the 10 years preceding the first cognitive assessment in 1997–1999 and tests were repeated in 2002–2004 and 2007–2009. Patients were a mean age of 56 years (range, 44 to 69) at their first cognitive assessment.
Cognitive testing included 4 tests assessing memory and executive function. Short-term verbal memory was assessed with 20 one- or two-syllable words, presented orally at 2-second intervals, and the participants had 2 minutes to recall the words in writing. Three timed tests assessed inductive reasoning via a series of 65 verbal and mathematical items of increasing difficulty, and 2 measures of verbal fluency. A global cognitive score was created by averaging the z scores of each test.
Results appeared online Jan. 15 at Neurology.
In men, there were no differences in cognitive decline among alcohol abstainers, quitters, and light or moderate alcohol drinkers who drank less than 20 g/d, so the group was combined to make up the reference category. However, drinking 36 g/d or more alcohol per day was associated with faster decline in all cognitive domains compared to the reference group.
The mean difference in 10-year decline in the global cognitive score was −0.10 (95% CI, −0.16 to −0.04); executive function was −0.06 (95% CI, −0.12 to 0.00); and memory was −0.16 (95% CI, −0.26 −0.05). Researchers calculated that the effect size is comparable to 2.4 extra years of cognitive decline in the global score, 1.5 extra years for executive function, and 5.7 extra years for memory.
In women, there was only weak evidence that heavy drinking was associated with a faster decline in executive function. But abstinence from alcohol was associated with faster decline in the global cognitive score and executive function, researchers found. Compared with those drinking 0.1 to 9.9 g/d of alcohol, female 10-year abstainers showed faster decline in the global cognitive score (−0.21; 95% CI, −0.37 to −0.04) and executive function (−0.17, 95% CI, −0.32 to −0.01). However, researchers noted, the number of female abstainers was small, and the category was likely to represent a group of selected individuals whose characteristics differed from other participants, including a higher percentage of nonwhite women.
Researchers wrote, “Our findings are in agreement with previous studies showing that moderate alcohol consumption is probably not deleterious for cognitive outcomes, but they also show that heavy alcohol consumption in midlife is likely to be harmful for cognitive aging, at least in men.”
The problem could be huge, since physicians aren’t really asking their patients about alcohol use. Only 1 in 6 adults, including binge drinkers, reported ever discussing alcohol consumption with a health professional, and only one-third of those who binged 10 or more times a month ever reported doing so, the CDC reported.
A survey done by ACP Internist in January 2013 found that more than a third of internists screening for alcohol misuse and abuse find that 10% or more of those screened turn up positive. A cover story in that issue of ACP Internist reported that internists have to wade through a mixed bag of messages when discussing alcohol with their patients.