a cousin of miesposo is a psychologist in SD, he works with addicts mainly, but in his workplace there are several other specialist who deal with all sort of issues. i understand they all charge lots of money... so definitely there are specialist who deal with mental illnesses, but this kind of help may not be available for the poor.
i saw an article last year about the state of public psychiatric hospital: ruined, run down, patients on the floor, really horrible place. lots of mentally ill people never see any professional help: they are locked at home, sometimes tied up. we sold all kinds of strong psycho meds in the pharmacy and they sold well. sometimes we'd have an emergency when clearly distressed family member would come in to buy injections saying the sick relative was aggressive and required several people to hold him down and tie up like a holiday ham in order to have him immobilized.
young children with obvious mental problems (born with down syndrome or any of the disease affecting both physical and mental state) are often abandoned. there is a house for sick children like this in POP, run by nuns. if you want i can hook you up with them, they always look for volunteers.
i often see visibly mentally ill people on the streets of POP. there are few who always seem to hang around the hospital. it is possible they were abandoned or run away. maybe they have family somewhere in DR who is looking for them or think they are dead.