Tales of family mental illnesses, substance abuse issues, and other challenges to normal daily functioning are not often passed down from one generation to another. And yet, they can explain why people disappear, certain relatives are never discussed, some relatives “won’t allow booze on the place,” etc.
Newspapers, death certificates, court records, state hospital records (or committals) can be some places to potentially find some information about these conditions–for some individuals if the records are not sealed. Not all people who suffered from these conditions will leave behind records documenting what was taking place in their life. The records that are left behind may be incomplete and inaccurate.
And remember that diagnosing these conditions was different in 1900 than it is today. The treatment, as well as the diagnosis, was different.