Middle age to older UK adults who consume even a few alcoholic drinks a week were observed to have a greater risk of brain atrophy. Authors note the study limitations and that it cannot demonstrate causality.

Medical Mythbusting Commentary for March 7, 2022

Source:
Those who consume even a few alcoholic drinks a week have smaller brains, research finds

Reference:
Associations between alcohol consumption and gray and white matter volumes in the UK Biobank