Social Security Disability

I have a brother,who has been unemployed for a number of years.(age 55)He lived with my parents for years,they have since both passed, He has had a social anxiety issue and most likely some other issues. He has been homeless,living in his truck in parking lots for over two years now... I have tried to help him him financially(as much as I can) and obtaining employment with no results, I can understand the results because,It is almost impossible to carry on a conversation with him. He did have a serious back injury back in the late1980's, this continues to be an issue for him,He has always been very frail and week,he suffers from "high blood pressure" migraines," he takes meds for that he receives from local Church Health Center, I am sure he has other medical issues that have not been diagnosed,as he does not have medical coverage.I do notice his mental status declining due to his situation,by the thing he says and his actions(He does not have a drug problem or illegal acts)