No major link has been established by researchers between alcohol intake and cognitive functioning in a Mendelian randomization study.
Many observational cohort studies have shown that moderate alcohol use is associated with better cognitive function.
However, since such studies are vulnerable to residual confounding by other lifestyle and physiologic factors, the researchers conducted a Mendelian randomization study, using aldehyde dehydrogenase 2 (ALDH2) genotype (AA, GA, or GG) as an instrumental variable in 2-stage least squares analysis.
The researchers had previously reported an association between reported alcohol intake and cognitive function from a larger group of subjects from the same study finding that women reporting occasional alcohol intake and men reporting occasional or moderate intake had better scores related to cognitive function than did abstainers.
In the present Mendelian study, the researchers found no significant association between groups defined by the ALDH2 genotype (as an "unbiased" estimate of alcohol consumption) and the two measures of cognitive functioning.
A problem with the present analysis is that ALDH2 genotypes explained only 3 percent of the variance in reported alcohol intake, which weakens the conclusions of the researchers.
Further, differences in the predominant type of beverage consumed (rice wine), and probably marked differences in drinking patterns between these subjects and Europeans and Americans, make it difficult to know what the implications of this study are for western industrialized societies.