Yah, the paper says that alcohol consumption explains 0.8% of the observed variance in grey matter, while age explains 54% of variance.

Following a few references, this paper seems to show a average 20%(!) reduction in brain volume from age 60 to 90: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2690968/ . Don't get old, folks...

>> Alcohol explained up to 0.8% of grey matter volume variance