Jan. 15, 2014 at 4:00 PM ET
Middle-aged men who drink more than two and a half drinks a day may speed their memory loss by nearly six years, according to a British study published Wednesday.
The study, released in the journal Neurology, did have good news for those who enjoy an occasional nip: It suggested that moderate alcohol intake could be good for the brain. But for male heavy drinkers, there was a significant, quantifiable loss of cognitive powers akin to premature aging.
Unlike most studies of how alcohol affects thinking and memory, the researchers were able to track cognitive changes over time by using 7,513 members of the so-called Whitehall II cohort, a study of British civil servants that’s been going on since 1985. About every four years since, the cohort has undergone a variety of examinations and answered questionnaires about their health habits, including alcohol intake.
Testing started in 1997 and was repeated at three intervals, the last in 2009 when the people ranged in age from 55 to 80.
There were three tests. One tested inductive reasoning. For example, people were asked to answer a series of questions like “Fish is to swim as bird is to ____,” and “Here are three figures: 325. Add the largest two figures together and divide the total by the smallest figure.”
The people were then tested for verbal fluency by writing down as many words beginning with the letter “S” as they could in one minute, and the names of as many animals as possible in one minute.
Short-term verbal memory was assessed by speaking words to the subjects, and then giving them two minutes to write down every one they could recall.
When the results were analyzed, and matched for consumption, it turned out that for men, consuming 36 grams of alcohol — about 2.5 drinks — or more per day “was associated with faster cognitive decline in all domains” compared to drinking lesser amounts.
The effect was especially harsh for memory. Male heavy drinkers added 5.7 years of memory decline. It's as if a 60-year-old man had the memory loss expected in a 66-year-old, lead author Séverine Sabia told NBCNews.com. Executive functions were affected too, with an extra 1.5 years tacked on for heavy drinkers.
The results held up, Sabia said, even after controlling for health factors like depression, which could lead people to drink and also has been shown to impair brain power.
Women were not nearly as affected, though women who abstained from alcohol for 10 years showed a faster cognitive decline than moderate female drinkers. Both Sabia and Dr. Meir Stampfer, a professor of medicine and epidemiology at Harvard Medical School, who also has studied cognitive decline in drinkers, cautioned against coming to any conclusions about the apparent gender difference.
While heavy drinking certainly seems to be bad for you, and not just for your mind, there's also some good news. There was no significant difference in cognitive decline between moderate drinking men and total abstainers. For women, moderate drinkers fared better.
Moderate drinking is defined as one drink a day for women and up to two drinks a day for men, the Centers for Disease Control and Prevention says.
Stampfer said his own work, and that of studies like Sabia’s, indicates that “moderate drinking is beneficial.”
Several mechanisms might be at work to confer this good effect, he said, but especially the way moderate alcohol intake benefits the cardiovascular system.
“There are shared risk factors,” between cardiovascular disease and cognition, he explained. People who suffer strokes, heart attacks and atherosclerosis often also suffer from mental decline due to impaired blood flow the brain. Because moderate boozing is beneficial for the cardiovascular system, the brain gets some benefit, too. “We know there is a strong relationship there.”
Think about that the next time you’re tipping your bartender.
Brian Alexander is a frequent contributor to NBC News and a co-author of “The Chemistry Between Us: Love, Sex, and the Science of Attraction.”