Look up the old state hospital cemeteries (Dixmont and Mayview/Morganza are local). Even if the hospital is knocked down and land has been sold say to Walmart or South Point the cemeteries remain, under pa law. They’re something and there old enough you can read the records in public search. Many list the cause of death as “general paresis of the insane”.

Edit- a word and also check in the Polk State School.