Bad news for casual drinkers – just one to two alcohol units a day results in lower brain volume, only getting worse as consumption increases, a new study suggests.
The study continues to challenge the belief that small amounts of alcohol are of no consequence – or are even healthy – finding that those with significant brain alterations from alcohol consumption may have cognitive impairments as a result.
“There is some evidence that the effect of drinking on the brain is exponential,” says former postdoc and co-corresponding author Remi Daviet in a statement.
“So, one additional drink in a day could have more of an impact than any of the previous drinks that day. That means that cutting back on that final drink of the night might have a big effect in terms of brain aging.”
Their results were published in the journal Nature.
For years, hopeful drinkers and conflicting science supported the notion of light-to-moderate alcohol consumption as a health-neutral concept, while drinks such as red wine were touted as a brilliant source of antioxidants. However, recent evidence is starting to highlight a dramatic difference in brain volume and microstructures of alcohol drinkers compared to those that refrain, and researchers from the University of Pennsylvania sought to delve deeper into this relationship.
The team took alcohol consumption data along with brain imaging of 36,678 healthy middle-aged and older people and controlled for potential confounding variables before looking for correlations between alcohol intake and changes in the brain. Brain volume was corrected for head size, so differences in that should not have an impact on the assessed effect of alcohol.
As alcohol consumption increased, there was a resulting decrease in overall brain volume, gray matter volume, and white matter microstructure. Essentially, brain size shrunk as the participant drank more alcohol.
“It’s not linear,” said Daviet. “It gets worse the more you drink.”
These results were in line with previous studies – however, there were also negative implications on the brain when the participant drank very few alcohol units, reaching as low as one to two. With just half a beer or a pint of beer per day, the brain saw changes equivalent to aging two years. As this increased to two to three units a day, the brain changed to the equivalent of three and a half years of aging.
Now, the researchers argue this calls into question government and health guidelines of safe alcohol consumption.
“These findings contrast with scientific and governmental guidelines on safe drinking limits,” says Henry Kranzler, director of the Penn Center for Studies of Addiction.
“For example, although the National Institute on Alcohol Abuse and Alcoholism recommends that women consume an average of no more than one drink per day, recommended limits for men are twice that, an amount that exceeds the consumption level associated in the study with decreased brain volume.”
The team is now turning their attention to whether the results remain the same if the alcohol consumption stays consistent, such as a beer a day every day, or when someone has no alcohol for a week but then binges at the weekend.