Blogspam.

Nature article: https://www.nature.com/articles/s43587-021-00138-z

>Based on retrospective case–control pharmacoepidemiologic analyses of insurance claims data for 7.23 million individuals, we found that sildenafil usage was significantly associated with a 69% reduced risk of AD (hazard ratio 0.31, 95% confidence interval 0.25–0.39, P < 1.0 × 10^–8).

Retrospective study, so no causation proved, of course. That will require an actual randomized clinical trial, which hasn't been done.