homeless mental health child listing as dependent?

My son is currently 22, does not go to school, does not work, and has been in and out of my house and homelessness. He has mental health issues but has not filed for disability as far as I know. I have paid a lot of money in medical bills, housing, food, clothes. I am not sure whether he qualifies as a dependent anymore. I do pay most of his expenses whether he is living with me or on the street. definitely more than 50%. but I am not sure because of his age, whether I can claim him. And at what age I have to stop claiming him. Thanks.