1-2 alcoholic drinks per day (7-14 drinks per week) can shrink the brain over time.

(Daviet et al., 2022)

Chronic alcohol consumption is linked to adverse changes in brain structure, loss of neurons, and reduction in brain size (brain atrophy). These effects are even more severe in older adults.

Daviet et al., 2022 a cohort study analyzed alcohol intake data from 36,768 participants (ages 40–69) in the UK Biobank in conjunction with data on brain structure.

Adverse effects of alcohol consumption were apparent in participants who consumed as little as 1-2 drinks per day (7-14 drinks per week), but adverse effects got more severe with increased alcohol intake. Adverse effects were shown in both the microstructural and macrostructural levels in the brain. Alcohol intake was associated with decreases in global brain volume, regional gray matter volume, and microstructure of the white matter.

Reference:

Daviet R, Aydogan G, Jagannathan K, Spilka N, Koellinger PD, Kranzler HR, Nave G, Wetherill RR. Associations between alcohol consumption and gray and white matter volumes in the UK Biobank. Nat Commun. 2022 Mar 4