Midlife alcohol consumption and later risk of cognitive impairment: a twin follow-up study.

In this prospective follow-up study, we monitored the effects of midlife alcohol consumption and drinking patterns on cognitive impairment risks in late life. 1,486 subjects recruited from the Finnish Twin Cohort were included in the analyses. Alcohol consumption data was obtained with structured questionnaires in 1975 and 1981, and subjects were contacted between 1999 and 2007 to conduct a telephone interview evaluating cognitive function. The mean follow-up period was 22.8 years (standard deviation 2.1 years). Both abstainers and heavy drinkers were found to have an increased risk of cognitive impairment in comparison to light drinkers (relative risk ratios 1.44; 95% confidence interval: 1.02-2.10 and 1.94, 1.10-3.44, respectively. Also, binge drinking at least monthly in 1975 and 1981, as well as more than two pass-outs due to excess drinking in 1981 were associated with an increased risk of cognitive impairment (1.98, 1.08-3.64 and 3.85, 1.51-9.83, respectively), even when excluding abstainers and controlling for total alcohol consumption. Subgroup analyses based on apolipoprotein E ε4 status suggest that the increased risk of cognitive impairment associated with being an abstainer is limited to subjects without an ε4 allele. Our results add to the evidence that light to moderate alcohol use is associated with a lower risk of cognitive impairment compared with higher levels of consumption. In addition, binge drinking was found to be an independent risk factor for cognitive impairment.