Anti social behavior.
Poverty.
Drug abuse.
Prostitution.
Racial discrimination.
Alcohol abuse.
Economic Deprivation.
Political Corruption.
John Steinbeck is the author of The Grapes of Wrath.
If this is asking for a personal opinion, then no. I do not believe there is any relationship or connection between sanity and intelligence because someone’s mental state or background doesn’t define their intelligence or thinking patterns. Some studies done over mental disorders such as BPD (borderline personality disorder) have found sufferers to be more intelligent and, ironically speaking, happier than the average person.