Several individual factors may increase a person's risk for becoming homeless and remaining homeless for a longer period of time:
Untreated mental illness can cause individuals to become paranoid, anxious, or depressed, making it difficult or impossible to maintain employment, pay bills, or keep supportive social relationships.
Substance abuse can drain financial resources, erode supportive social relationships, and make exiting from homelessness extremely difficult.
Co-occurring disorders. Individuals with co-occurring mental health and substance use disorders are among the most difficult groups to put in stable housing and treat. This is due to the limited availability of integrated mental health and substance abuse treatment in most locations.
Other circumstances. People may become homeless for a variety of other reasons, including divorce or separation, domestic violence, chronic or unexpected health care expenses, release from incarceration, or release from foster care.
With care and prevention, treatment is possible, but those people have to want it or seek it out. How do you tell a person to get help if they think it is the world against them?
Mental illness is should never be ignored and it may not be easy to help some people, but having the services always available is one way to increase the chances for change.
Some people on the streets may have ended up there with different circumstances than mental illness. When faced with this, depression and other mental disorders might be a result of being homeless instead of the cause it may have been the product.