https://goo.gl/s7XHom
The relationship between alcohol use and cognitive function is non-linear. Consuming more than one UK standard unit of alcohol per day is detrimental to cognitive performance and is more pronounced in older populations.
In 13 342 weekly drinkers drawn from UK Biobank, 5-year change in mean RT and IIV in RT were found to have curvilinear associations with alcohol consumption. Cognitive performance improved as alcohol consumption increased up to 10 g/day and then deteriorated as alcohol consumption increased beyond 10 g/day. As individuals age, this deleterious effect of alcohol on cognitive performance became more pronounced.