So, you only drink in moderation? It’s probably doing more damage than you think

It turns out the old moniker of everything being fine in moderation might not be true, at least when it comes to drinking.

Heavy drinking has been known to cause health problems, specifically damage to the brain. But a new study shows even moderate drinking will do significant damage long-term.

The study, published Tuesday in the British Medical Journal, measured the weekly alcohol intake and cognitive performance of 550 men and women over a 30-year period. None of the participants were classified as alcoholics by the end of the study, and the median consumption across participants was 11.5 units per week. A unit is not necessarily the same as a drink – for example, a unit of beer is eight ounces, while a British pint is 16 ounces. So, a British pint would equal two units.

Participants underwent an MRI scan and both verbal and written tests at various stages of the study. The study authors categorized people as abstinent (a unit or less per week), light drinkers (between one and seven units per week), moderate drinkers (women who had between seven and 14 and men who had between seven and 21 units per week) and unsafe drinkers (people who exceeded moderate drinking amounts).

The MRIs showed both the hippocampus, which consists of gray matter and is associated with memory, and white matter of the brain were negatively affected by even moderate drinking, not just heavy drinking. After taking into account age, sex, education and social habits, the authors found 35 percent of those who were abstinent from drinking had shrinkage on the right side of the hippocampus at the end of the 30-year study.

But for those who were moderate drinkers, 65 percent of those participants had shrinkage, and 77 percent of unsafe drinkers had the same.

White matter of the brain, which transmits information throughout the brain, was also weakened by even moderate drinking. White matter abnormalities have been associated with autism.

In tests, drinking seemed to affect specific topics but not others. For example, participants categorized as moderate or unsafe drinkers had a 14 percent greater reduction over the 30-year period in their performance on a lexical fluency test compared to abstinent drinkers. A lexical fluency test involves asking the participant to name as many words as they can within a minute that start with a specific letter.

However, other tasks such as word recall were not affected by drinking habits.

Despite the study’s findings, experts such as Dr. Doug Brown, director of research and development at Alzheimer’s Society, told the Guardian that people should not think they need to stop drinking completely.

“Although this research gives useful insight into the long-term effects that drinking alcohol may have on the brain, it does not show that moderate alcohol intake causes cognitive decline,” Brown said. “However, the findings do contradict a common belief that a glass of red wine or champagne a day can protect against damage to the brain.”

The study’s authors said their findings should call into question the designated “safe” levels of drinking in certain countries. In the U.S., heavy drinking is typically defined as consuming 15 drinks or more per week for men and eight drinks or more per week for women, according to the Centers for Disease Control and Prevention.

This story was originally published June 7, 2017 at 7:37 AM with the headline "So, you only drink in moderation? It’s probably doing more damage than you think."