Homelessness and mental health

A study in Western societies found mental illness, alcoholism, and drug dependency to be more prevalent among homeless people than among the general population. A 2009 US study estimated that 20–25% of homeless people, compared with 6% of the non-homeless, have severe mental illness. Other estimates vary. One 2003 study out of California suggests that 20-40% of the homeless have a severe mental illness. A 2024 systematic review and meta-analysis by JAMA (the Journal of the American Medical Association), consisting principally of Canadian, German, and American studies, found that 67% of the unhoused had a mental health disorder, with a 77% lifetime mental health disorder prevalence among those who are or have been homeless.

In January 2015, the most extensive survey ever undertaken found 564,708 people were homeless on a given night in the United States. Depending on the age group in question and how homelessness is defined, the consensus estimate as of 2014 was that, at any given time, 45% of the American homeless—250,000 individuals—were mentally ill and that at least 25% of the homeless—140,000 individuals—were seriously mentally ill, with even higher numbers if these were annual counts rather than point-in-time counts.

Being chronically homeless also means that people with mental illnesses are more likely to experience catastrophic health crises requiring medical intervention or resulting in institutionalization in the criminal justice system. Though most homeless people do not have a mental illness, those facing homelessness are struggling with psychological and emotional distress. The Substance Abuse and Mental Health Services Administration found that, in 2010, 26.2 percent of sheltered homeless people had a severe mental illness.

Studies have found that there is a correlation between homelessness and incarceration. Those with mental illness or substance abuse problems were found to be incarcerated more often than the general population. Fischer and Breakey have identified the chronically mentally ill as one of the four main subtypes of homeless persons, the others being street people, chronic alcoholics, and the situationally distressed.

The first documented case of a psychiatrist addressing the issue of homelessness and mental health was that of Karl Wilmanns in 1996.