The results of numerous studies have been clear: heavy drinkers have changes in brain size and structure that are linked to cognitive impairments. Researchers have now shown that even modest consumption of alcohol such as a few glasses of wine or beers every week could also pose a risk to brain health. An analysis of data from over 36,000 individuals revealed that light-to-moderate consumption of alcohol was linked to a reduction in the overall volume of the brain.1✅ JOURNAL REFERENCE
The greater the level of alcohol consumed, the stronger the association. For example, as average drinking in 50-year-olds increased from half a beer (1 unit) per day to a pint of beer (2 units) there were associated brain changes equal to aging 2 years. Progressing from 2 to 3 alcohol units at the same age was equivalent to aging 3.5 years.
Many studies have looked at the link between alcohol consumption and the health of the brain, with unclear outcomes. Although there is strong evidence that heavy drinking leads to brain structure changes, which includes reductions in white and gray matter in the brain, other research has suggested that moderate consumption of alcohol might not have an effect, or even that light alcohol consumption could benefit the brain in older individuals.
However, these studies did not employ the strength of large datasets that this current study did, which examined MRIs from over 36,000 individuals in the Biobank that contains medical and genetic data from half a million middle-aged and older people, which can be made use of for calculating the volume of gray and white matter in various brain areas.
The researchers controlled for confounding variables such as sex, age, height, socioeconomic status, handedness, county of residence, genetic ancestry, and smoking status. The brain-volume data was also corrected for the overall size of the head.
The Biobank participants had replied to questions regarding their levels of alcohol consumption, from total abstinence to an average of 4 or more daily alcohol units. When the participants were grouped by average levels of consumption, and taking into account other characteristics of the individuals, it was discovered that the white and gray matter volume was reduced.
Progressing from 0 to 1 unit of alcohol didn’t make much of a brain volume difference, but progressing from 1 to 2 or 2 to 3 daily units was linked to both white and gray matter reductions.
The associations remained even after the heavy drinkers were removed from the analyses. The reduced brain volume was also not localized to any one area of the brain.
The brain size reductions associated with drinking were compared to those that happen with aging to give an indication of the impact. According to the researcher’s modeling, each additional daily alcohol unit consumed was reflected in a greater brain aging effect. Although progressing from 0 to a daily average of 1 alcohol unit was linked to the equivalent of half a year of aging, the difference between 0 and 4 drinks was over 10 years of aging.
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