We all lose some mental sharpness as we age, but men who drink heavily at midlife can expect a steeper, faster decline in memory and thinking skills a decade down the road, a new study suggests.
The study, published Wednesday in the journalNeurology, defines heavy drinking for men as more than 36 grams of alcohol a day, the equivalent of 2.5 drinks. Men who drink less or don't drink at all still lose some cognitive ground, the researchers say, but not as much. The study looked at women but found no clear results for them.
The study suggests lighter drinking does not contribute to cognitive decline.
"The findings are in agreement with previous studies and suggest that moderate alcohol consumption is probably not deleterious for cognitive outcomes," says lead researcher Séverine Sabia, an epidemiologist at University College-London.
Some studies even suggest light or moderate drinking might be better for aging brains than abstinence, but the new study did not show that, she says. There was a hint that non-drinking women fared worse than moderate drinkers, but there were not enough abstaining women in the study to make the results convincing, Sabia says. The study suggested faster cognitive declines for female heavy drinkers, but those results were not statistically significant.
The study involved more than 5,000 men and 2,000 women, all white-collar workers, participating in a long-running health study in the United Kingdom. Starting at an average age of 45, the participants told researchers how much they drank. A decade later, they started taking tests of memory and executive function, the kind of thinking used in planning, organizing and regulating behavior.
Researchers found no major differences among men who abstained, quit drinking during the study or had up to two drinks a day. The men who averaged 2.5 drinks or more lost ground on memory tests at a rate nearly six years faster than other men; they declined on executive function nearly two years faster.
It's important to note that some of the men in the heavy-drinking group drank as much as eight drinks a day on average, says Sara Jo Nixon, a professor of psychiatry at the University of Florida-Gainesville. It would be wrong to assume, she says, that men who drink 2.5 drinks a day are at the same risk as the heaviest drinkers or that there is a sharp rise in risk at that level.
She notes that the researchers did not collect information on binge drinking or how much participants were drinking at the time of the mental tests.
Still, she says, the study is "provocative." She says it adds evidence that "what we do in midlife is important," and "drinking across a range could be detrimental for cognitive integrity, even before individuals get elderly."
In the USA, health officials define a drink as 14 grams of alcohol, the amount in 12 ounces of beer, 5 ounces of wine or a 1.5-ounce shot of liquor, according to the federal Centers for Disease Control and Prevention. Moderate drinking is defined as up to two drinks a day for men, but just one drink for women, because the same amount of alcohol typically affects women more strongly.
In addition to cognitive risks, drinking is associated with increased risks of breast cancer in women and increases in car crashes, violence and liver disease. Some evidence suggests moderate drinking is beneficial for heart health in some older adults.
The new study fits into a theory that heavy drinking tends to "accelerate aging," especially after midlife, says Marlene Oscar Berman, a researcher in neuropsychology at Boston University. The participants ranged in age from 44 to 69 when they took the first cognitive tests, and "that's just when it starts to hit," she says.