The evidence for the relationship between alcohol, coffee and tea and cognitive deficits/benefits
has been confounding to date. This meta-analysis aimed to assess the current evidence
available in terms of the dose–response relationship between alcohol, coffee or tea
consumption and cognitive deficits.
Interestingly, it concluded that, based on the studies and data reviewed, whilst excessive
consumption of alcohol is known to have adverse health effects, light consumption of alcohol
(<11 g/day) and of coffee (<2.8 cups/day) are associated with reduced risk of cognitive deficits.
It also concludes that the cognitive benefits of green tea consumption increase with its daily
consumption.

The full text can be accessed here.

Alcohol, coffee and tea intake and the risk of cognitive deficits: a dose-response meta-analysis. Ran, L.S., Liu, W.H., Fang, Y.Y. et al. (2021) Epidemiology & Psychiatric Sciences. 30 (e13).