Fact No. 9 reflects the seriousness of mental health and substance abuse. While it is not a fair stereotype, up to 1/4 of those who find themselves homeless suffer from mental illness and about half of those also have substance abuse issues. For some people, substance abuse is a form of self-medication. Some folks became homeless due to addiction or mental illness and some only begin using illicit substances and/or alcohol because of their homeless status. There are many sides to this Pandora’s box.