Fewer car accident deaths, leading to more elderly people, which inevitably means a higher population of people with Alzheimers.

(Unless people highly predisposed to dying in car accidents are also highly predisposed to mudering people who will have, but don’t yet have, Alzheimers. But that seems sufficiently unlikely for the purposes of this hypothetical.)

Jokes aside, the serious answer depends on whether the link is causative or merely collerative.

No taxi drivers