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The research, which used a data set of more than 36,000 adults, revealed that going from one to two drinks a day was linked to changes in the brain equivalent to aging two years. Heavy alcohol use was associated with an even higher number.
The science on binge drinking and the brain is clear: the two do not have a healthy relationship. Heavy drinkers have alterations in brain size and structure that are associated with cognitive deficits.
An analysis of data from more than 36,000 adults, led by a team from the
University of Pennsylvaniafound that mild to moderate alcohol consumption was associated with reductions in overall brain volume.
The link became stronger the higher the level of alcohol consumption, the researchers showed. For example, in people age 50, as the average alcohol consumption among people increases from one unit of alcohol (regarding half a beer) a day to two units (a pint of beer or a glass of wine), Associated changes occur in the brain. equivalent to aging two years. Going from two to three units of alcohol at the same age was like aging three and a half years. The team reported their findings in the journal
«Nature Communications».
“The fact that we have such a large sample allows us to find subtle patterns, even between drinking the equivalent of half a beer and one beer a day,” says Gideon Nave, the study’s corresponding author and a Penn’s Wharton faculty member. College.
He collaborated with former postdoc and co-corresponding author Remi Daviet, now at the
University of Wisconsin-Madisonand colleagues from the Perelman Reagan Wetherill School of Medicine, also corresponding author of the study, and Henry Kranzler, as well as other researchers.
“These findings are in contrast to scientific and government guidelines on safe drinking limits,” says Kranzler, who directs the Penn Center for Addiction Studies. “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, the recommended limits for men are double that, an amount that exceeds the level of consumption associated with brain decline in the study. volume”.
Extensive research has examined the link between drinking and brain health, with mixed results. While there is strong evidence that binge drinking causes changes in brain structure, including sharp reductions in gray and white matter throughout the brain, other studies have suggested that moderate levels of alcohol use may not have an impact, or even that moderate alcohol consumption might benefit the brain. in older adults.
However, these earlier investigations lacked the power of big data sets. Testing massive amounts of data for patterns is the specialty of Nave, Daviet, and their colleagues, who have conducted previous studies using the UK Biobanka dataset containing genetic and medical information on half a million middle-aged and older British adults.
They used biomedical data from this resource in the current study, specifically looking at brain MRIs from more than 36,000 adults in the Biobank, which can be used to estimate white and gray matter volume in different brain regions.
“Having this data set is like having a microscope or a telescope with a more powerful lens,” says Nave. “You get better resolution and you start to see patterns and associations that you mightn’t before.”
To gain an understanding of possible connections between drinking and the brain, it was critical to control for confounding variables that might cloud the relationship. The team controlled for age, height, hand, gender, smoking status, socioeconomic status, genetic ancestry and county of residence. They also corrected brain volume data for total head size.
Volunteer participants in the Biobank had answered survey questions regarding their levels of alcohol consumption, ranging from complete abstention to an average of four or more units of alcohol per day. When the researchers grouped the participants by average consumption levels, a small but apparent pattern emerged: Gray and white matter volume was reduced that might otherwise be predicted by other characteristics of the individual.
Going from zero to one unit of alcohol didn’t make a big difference in brain volume, but going from one to two or two or three units a day was associated with reductions in both gray and white matter.
«It’s not linear,” says Daviet. “It gets worse the more you drink».
Even removing heavy drinkers from the analyses, the associations remained. The lower brain volume was not localized to any brain region, the scientists found.
To give an idea of the impact, the researchers compared the reductions in brain size linked to drinking to those that occur with aging. According to their model, each additional unit of alcohol consumed per day was reflected in a greater aging effect on the brain. While going from zero to a daily average of one unit of alcohol was associated with the equivalent of half a year of aging, the difference between zero and four drinks was more than 10 years of aging.
In future works, the authors hope to take advantage of the UK Biobank and other large data sets to help answer additional questions related to alcohol use. “This study looked at average consumption, but we’re curious if drinking one beer a day is better than none during the week and then seven on the weekend,” says Nave. “There is some evidence that heavy drinking is worse for the brain, but we haven’t looked at it closely yet.”
They would also like to be able to pin down causality rather than correlation more definitively, which may be possible with new longitudinal biomedical data sets that follow young people as they age.
And while the researchers stress that their study only looked at correlations, they say the findings may prompt drinkers to reconsider how much they drink.
“There is some evidence that the effect of drinking on the brain is exponential,” says Daviet. “So one more drink a day might have more impact than any of the previous drinks that day. That means forgetting the last drink of the night might have a big effect in terms of brain aging.”
In other words, says Nave, “the people who stand to benefit the most from drinking less are the people who are already drinking more.”
