A study published in Nature in March seems to offer some of the most compelling evidence yet that even moderate drinking can harm the brain.
The world of alcohol research appears a little confused at the moment, at least from a public-messaging standpoint. A study published in Nature in March seems to offer some of the most compelling evidence yet that even moderate drinking can harm the brain.
After examining brain scans from more than 36,000 middle-aged and older people from the UK Biobank, researchers found that 50-year-olds who drank an average of one 175 millilitre (6 oz) glass of wine or half-litre (roughly 1 US pint) can of beer per day over the past year had brains that appeared 1.5 years older than counterparts who drank half that amount or not at all. Aging increased with alcohol consumption, the researchers wrote.
The study is one of the largest addressing the health impact of moderate drinking on the brain to date. Researchers defined moderate drinking as up to 14 drinks per week, and light as more than one drink per week but less than seven. But a lot of questions remain open.
Though the results of the brain study seem straightforward at first glance, digging a little deeper reveals how much we still don’t know. Patricia Molina, who directs Louisiana State University’s Alcohol and Drug Abuse Center of Excellence, said it remained unclear what the effects of two years of brain shrinkage — which caused the appearance of aging — were on cognition and behavior.
Several lines of evidence show a relationship between loss of brain volume and cognitive impairment, she said. But she is also unaware of any conclusive studies showing a direct relationship between specific percentages of decreased brain volume and clinical manifestations that are evident to people or their doctors. Molina said the study’s design also made it difficult to answer questions about how its results compare with the shrinkage caused by other activities and illnesses known to cause a decrease in brain matter, such as a lack of physical fitness or Huntington’s disease. “A meta-analysis would be the closest way of getting to the answer,” Molina said. In other words, someone would have to look at the entire body of literature and analyse the results in a way that allows such comparisons to be made.
And another reason why such comparisons are hard to track, Molina said, is that different activities or illnesses cause different shrinkage in different places. Lounging around all day and eating only processed food, for example, might cause shrinkage in a different area of the brain than Huntington’s disease. Then there’s the chicken-and-egg dilemma. Could it be that people inclined to drink alcohol regularly just have smaller brains in general than those who choose to abstain?
“That is a distinct possibility,” Molina said. “The only way of answering that question is by collecting brain images from early life.” Researchers are looking to address this question through the Adolescent Brain Cognitive Development study, Molina said. That study tracks changes in brain volumes over time while collecting data on alcohol and drug use.
But isn’t red wine good for you? The evidence that binge drinking is harmful for the body and brain is conclusive. But when it comes to moderate drinking, things get a little trickier. A number of studies published over the past few decades, including one presented just a day before the brain study, appear to claim moderate drinking can actually be good for you. Analysing data also obtained through the UK Biobank from about 312,000 current drinkers, the researchers found that consuming the alcohol equivalent of about 5 ounces of wine with meals per day for women and 10 ounces for men was associated with a lower risk of developing type 2 diabetes.
