[albertgoeswoof]

There might be uncontrolled factors specific to French drinkers. E.g. Government policies (taxes on types of alcohol, licensing laws), cultural difference (like drinking later in the evening, with food, or regularly vs binge drinking) etc. etc.

It's not that those things make this completely irrelevant to you, it's that the blanket statement "Alcohol use largest risk factor for dementia" is not proven by this study, due to the earlier commentor's points.