A British study following 550 adults over 30 years from 1985 has found that those who reported higher levels of alcohol consumption were more often found to have a shrunken hippocampus, with the effect greater for the right side of the brain. Such shrinkage was found in 35% of those who didn’t drink, but 65% for those who drank an average 2-3 units daily, and 77% for those who drank 30 or more units a week.

The structure of white matter was also linked to how much individuals drank.

Those who drank more did worse on a test of lexical fluency (“Name as many words starting with (a letter) as you can in a minute”), however no differences were found in performance in other tasks such as word recall, or naming words in a specific category, so that seems oddly specific.

Factors such as age, sex, social activity and education, were taken into account in the analysis. However, the majority of the study’s participants were men, and self-reports of alcohol consumption are often inaccurate with people underestimating how much they drink.

Perhaps the most important conclusion to draw from this study is that alcohol consumption of up to 13 units weekly was not associated with these negative changes – so rather than taking this as evidence of challenge to the research supporting moderate drinking, it should perhaps be taken as evidence of where the line should be drawn.

Units are defined as 8g of alcohol. In the U.S., a typical 12-ounce beer or 5-ounce glass of wine contains 14 g of alcohol.