I'm unsure how much alcohol I should drink.

I'm perfectly happy abstaining. And I know that my memory and computer programming abilities are temporarily impaired by even one drink.

But there's fairly persuasive evidence that several drinks daily causes old people to live longer. With the notable exception of social isolation (people tend to drink more when they're socializing), just about everything I can imagine was controlled for.

Background: Growing epidemiological evidence indicates that moderate alcohol consumption is associated with reduced total mortality among middle-aged and older adults. However, the salutary effect of moderate drinking may be overestimated owing to confounding factors. Abstainers may include former problem drinkers with existing health problems and may be atypical compared to drinkers in terms of sociodemographic and social-behavioral factors. The purpose of this study was to examine the association between alcohol consumption and all-cause mortality over 20 years among 1,824 older adults, controlling for a wide range of potential confounding factors associated with abstention. Methods: The sample at baseline included 1,824 individuals between the ages of 55 and 65. The database at baseline included information on daily alcohol consumption, sociodemographic factors, former problem drinking status, health factors, and social-behavioral factors. Abstention was defined as abstaining from alcohol at baseline. Death across a 20-year follow-up period was confirmed primarily by death certificate.

Results: Controlling only for age and gender, compared to moderate drinkers, abstainers had a more than 2 times increased mortality risk, heavy drinkers had 70% increased risk, and light drinkers had 23% increased risk. A model controlling for former problem drinking status, existing health problems, and key sociodemographic and social-behavioral factors, as well as for age and gender, substantially reduced the mortality effect for abstainers compared to moderate drinkers. However, even after adjusting for all covariates, abstainers and heavy drinkers continued to show increased mortality risks of 51 and 45%, respectively, compared to moderate drinkers.