John Hopkins University continuously updated a repository of federal and private funding opportunities that are intended for postdoctoral investigators. The opportunities are pre-sorted chronologically and alphabetically, and can be searched by funding amount and subject matter.
Download the most recent listThe AlzForum also colleates a list here – https://www.alzforum.org/grants
Dementia Researcher also has a list – https://www.dementiaresearcher.nihr.ac.uk/funding-calls/