A US scientist has poured cold water on research that suggests moderate alcohol consumption provides a cognitive boost at midlife.
Robert Hauser, a university of Wisconsin-Madison professor of sociology, claims that a number of studies that have reported middle-aged and older people who drank moderate amounts of alcohol scored higher on a variety of cognitive measures were 'deeply flawed'.
His remarks follow a new study that he co-conducted that examined the relationship of alcohol intake and cognition on people in their mid-50s. Published in the July issue 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 drew data through the Wisconsin Longitudinal Study (WLS), a massive study that has 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.
According to Jeremy Freese, co-author of the study and also a UW-Madison professor of sociology, the new WLS study is a demonstration of "the importance of having longitudinal data in studies of alcohol use and cognition. You can't be sure of any effects unless you know what (subjects') cognition was like early in life".
According to the researchers, 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.
"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," said Hauser.
Hauser further stressed that the new WLS results did not show that moderate alcohol use had 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," continued Hauser."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."
He maintains that the next steps in terms of assessing the effects of moderate drinking on cognitive ability will be to apply a broader set of measures of cognitive outcomes as the WLS cohort approaches old age, and to gather a more detailed history of alcohol use by the study's subjects.