While moderate drinking - one to less than three drinks per day - is linked to a decrease in mortality in middle-aged and older adults, there is also concern that the health benefits of moderate drinking have been overestimated. A new study of the association between drinking and mortality during a 20-year period, which controlled for confounding factors such as previous problem drinking, confirms an association of moderate drinking and reduced mortality among older adults.
Results will be published in the November 2010 issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
"Although alcohol misuse is linked to many medical conditions, considerable epidemiological evidence indicates that moderate alcohol use is related to reduced total mortality," explained Charles J. Holahan, a professor in the department of psychology at The University of Texas at Austin and corresponding author for the study. "We expected that a substantial part of the health benefits associated with moderating drinking were due to confounding factors associated with alcohol abstention. For example, abstainers may include former problem drinkers with health problems and individuals who are atypical in terms of sociodemographic and social-behavioral factors that may increase health risk."
"None of the studies that have examined the association of drinking and mortality and cardiovascular disease have been experimental studies in which a group of people was randomly chosen to drink a particular amount of alcohol or to not drink alcohol," observed Alison A. Moore, professor of medicine and psychiatry in the David Geffen School of Medicine at the University of California, Los Angeles. "All have been observational studies, meaning those in which persons who consume varying amounts of alcohol are compared with those who don't. Because conditions in these observational studies are not controlled and the characteristics of persons who choose to drink varying amounts of alcohol or not differ quite a bit, it is impossible to prove that alcohol consumption causes reduced risks for coronary heart disease, diabetes or mortality."
For this study, using data gathered from a larger study of late-life patterns of drinking and related problems, researchers followed 1,824 older adults (1,142 men, 682 women) between the ages of 55 and 65 years of age - who were former or current drinkers - for 20 years. The information collected included: daily alcohol consumption, sociodemographic factors, former problem-drinking status, health factors, and social behavioral factors. Death was confirmed primarily by a death certificate.
"Controlling only for age and gender, mortality was highest among abstainers and heavy drinkers and lowest in moderate drinkers," said Holahan. "Controlling for former problem drinking status, existing health problems, and key sociodemographic and social-behavioral factors 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 49 percent and 42 percent, respectively, compared to moderate drinkers."
"In other words, the association of moderate drinking and reduced mortality among older adults is reduced but still present when taking into consideration factors that affect both alcohol consumption and mortality," said Moore. "For example, socioeconomic status has been a consistent factor in the link between alcohol consumption and mortality. That is, those with higher income and/or education are less likely to be abstainers and to die."
Thus, the health benefits of moderate drinking ae complicated because a number of underlying health risks are correlated with later life abstention, Holahan noted.
"Our findings demonstrate that abstainers were significantly more likely to have had prior drinking problems, to be obese, and to smoke cigarettes than moderate drinkers and scored significantly higher than moderate drinkers on health problems, depressive symptoms, and avoidance coping," he said. "In addition, abstainers were significantly lower than moderate drinkers on socioeconomic status, physical activity, number of close friends, and quality of friend support and significantly less likely to be married than moderate drinkers. Moreover, all of these factors that were associated with abstention significantly predicted mortality."
Both Holahan and Moore reiterated that any health benefits are linked to moderation. "Older persons drinking alcohol should remember that consuming more than two drinks a day exceeds recommended alcohol consumption guidelines in the U.S. and is associated with increased falls, a higher risk of alcohol use problems, and potential adverse interactions with medications," said Holahan. "Moreover, nondrinkers should not start drinking to try to enhance their health, and individuals who are or plan to become pregnant, or have alcohol problems or medical conditions that could be worsened by alcohol should not drink."