"Don't believe it if you're told moderate drinking is good for you cognitively," says Robert Hauser, a University of Wisconsin-Madison professor of sociology and a co-author of a new study that examined the relationship of alcohol intake and cognition on people in their mid-50s.
"The research is deeply flawed."
During the past decade, a number of studies have reported that middle-aged and older people who drank moderate amounts of alcohol scored higher on a variety of cognitive measures. What those studies lack, according to Hauser and his colleagues, is the kind of baseline data - namely, information on cognitive ability from relatively early in life - that could explain any apparent benefits of alcohol.
Conversely, the study found no evidence that moderate alcohol intake reduces cognitive ability in middle age.
"The claims about (moderate drinking) being bad or good aren't really based on good evidence," Hauser says.
Published in the current issue (July) of the journal Alcoholism: Clinical and Experimental Research, the study was led by Dean Krahn of the William S.
Middleton Memorial Veterans Hospital in Madison, and was drawn from data compiled through the Wisconsin Longitudinal Study (WLS), a massive study that has continuously tracked the lives and social histories of nearly 10,000 people who graduated from Wisconsin high schools in 1957.
Known as the "Happy Days study," the WLS includes a variety of measures of the high school class of 1957, including baseline cognitive ability test scores from the freshman and junior years of high school and educational attainment. In 1992, at age 53, study participants were given an abstract reasoning test and alcohol intake was measured.
Looking at these measures for the 53-year-olds, the Wisconsin researchers found that both men and women who had low levels of alcohol consumption did better on the abstract reasoning task than either non-drinkers or heavy drinkers. But after adjusting for cognitive ability measures taken in adolescence and educational attainment, the apparent benefits of moderate drinking on cognition disappear.
The significant result of the new WLS study is a demonstration of "the importance of having longitudinal data in studies of alcohol use and cognition," says Jeremy Freese, a co-author of the study and a UW-Madison professor of sociology. "You can't be sure of any effects unless you know what (subjects') cognition was like early in life."
The new WLS results underscore the potential for misinterpretation of results that capture alcohol use and cognition at a moment in time, and cast doubt on the recent body of evidence that moderate drinking can have some benefits, says Hauser.
"On the basis of these findings, I would be very suspicious of any study that looked at a point in time at cognitive ability and the use of alcohol.
They are likely to be misleading," he says.
Hauser says it was important to note, as well, that the new WLS results did not show that moderate alcohol use has any deleterious effects on cognition.
An intriguing insight from the study, according to Hauser, is the relationship between cognitive ability, educational attainment and alcohol use.
"I think there is a bit of a mystery here," Hauser says. "Why are people with higher cognitive abilities more likely to be more moderate in their drinking habits than they are to be either non-drinkers or heavy drinkers? For people who go far in school, moderate drinking is the norm, but that does not explain the entire effect of cognitive ability."
Source: University of Wisconsin Press Release.