According to the Health Care for the Homeless Clinicians' Network (2000) "Co-occurring mental illness and substance abuse makes it more likely that people will be chronically homeless." (cited in Finnerty, 2008) Factors that are known to contribute to homelessness in those with co-occurring mental illness and substance abuse include factors such as: (1) Financial problems; (2) Loss of family support; (3) Severity of symptoms; and (4) Time spent in institutions such as jails or hospitals. (Brunette, Mueser and Drake, 2004 in: Finnerty, 2008) Padgett and Struening (1991) state that substance abuse and mental disorders "…increase the health care needs of homeless persons, whose primary source of care is often the emergency room. The work of Padgett et al. (2006) reports having interviewed a group of women who had been previously homeless. The interviews examine the women in terms of their history of mental illness, substance abuse and traumatic events. It was found that nine of the thirteen women in the study "reported traumatic events, including rape and childhood sexual abuse, violence, or betrayal of trust. A history of substance abuse was reported in nine of the thirteen women. Hawkins and Abrams (2007) conducted a study on mental illness and homeless persons and specifically 39 individuals with mental illness in New York City. These individuals had abused drugs or alcohol and who were homeless. The study found that the majority of these individuals "had few friends or relationships with others." (Finnerty, 2008)

Rosenthal (2007) examined co-occurring disorders among young, recently homeless persons in Melbourne, Australia, and Los, Angeles, United States. The study was inclusive of 162 individuals in Melbourne and 259 individuals in Los Angeles. The individuals in this study were questioned concerning mental health and problems with alcohol and drugs both at the start of the study and six months and one year later. The results of the study state that there was a low rate of co-occurring mental illness and substance abuse among young homeless and "at all three points in time, the majority of the individuals had neither a mental illness, nor problems with drugs or alcohol. One problem with this study is that it only questioned individuals between ages 12-20 years old. Most serious mental illness does not develop until after the age of 20." (Finnerty, 2008)

A report published by the Health Care for the Homeless Clinicians' Network (2000) conducts an examination of "mental illness, substance abuse, and possible treatment policies. Treatment is necessary for those with a mental illness and the longer one goes without treatment, the worse their illness gets and they become more difficult to treat. Treatment is necessary for this group of homeless persons, but is extremely difficult without stable housing." (Finnerty, 2008)

According to HCH Clinicians (2000) "Patients with severe mental illnesses who are housed have fewer complications, and are much less likely to have co-occurring disorders that exacerbate their illness"(p. 2). Homeless people have multiple needs and need individual care and long-term service if they hope to get better." (Health Care for the Homeless Clinicians' Network 2000 cited in Finnerty, 2008)

The work of Liebow (1993) states that life is more difficult for the population of women who are also affected by mental illness and substance abuse as these individuals are those with the greatest need for shelter and health care, however, this group rarely receives shelter or health care service. In fact, Liebow states that the stress of being homeless only serves to exacerbate the problems of mental illness and substance abuse. Finnerty states that studies have found that "mental illness makes homelessness even worse and increases the likeliness that one will remain homeless. Other studies have found that treatment is necessary to overcome homelessness." (cited in Finnerty, 2008)

It is reported that The Criminal Justice Task Force Report on Mental Health and Criminal Justice in Tennessee made recommended through the Office of Housing and Homeless Services that TDMHDD "work toward increasing appropriate housing options for persons with serious mental illness who are engaged with the criminal justice system." (Tennessee Department of Mental Health and Developmental Disabilities, 2010) Findings of the THDA SJR 279 Housing Report (2000) states the following conclusions: (1) Approximately 15% of persons with severe and persistent mental illness receiving case management are housed inappropriately. One can assume that this percentage might be considerably higher among other segments not receiving services at all, such as homeless persons' (2) In all areas of the state and among every subgroup of the population surveyed, the primary barrier to appropriate housing was insufficient income to pay for monthly expenses; (3) The...

(Tennessee Department of Mental Health and Developmental Disabilities, 2010)
It was established by the National Technical Assistance Center for State Mental Health Planning's Housing for Persons with Psychiatric Disabilities: Best Practices for a Changing Environment that there is a responsibility of the state and community mental health systems to focus on housing "as a necessary component of recovery and community support; (2) The focus of housing planning should be on "permanent housing that is affordable." (3) Planning for housing and planning for support of people needing recovery should be closely linked. (4) The most effective method to the promotion of recovery and re-integration into society is a combination of professional services that are staffed both by individual with and without a history of psychiatric disabilities combined with peer support and consumer operated services and natural support systems in the community. (5) The leadership of the state mental health agency needs to view assistance for rental as an integral part the strategy of a design to increase access to integrated housing. (6) Rental assistance activities should be developed in the context of an overall housing policy that supports a variety of activities designed to increase the availability of integrated housing. This includes the development of state policy in regards to housing and residential services. (7) Housing discrimination against people with psychiatric disabilities is a major national problem that requires urgent attention. (8) Legal protections and tools, such as those found in the Fair Housing Amendments Act, Section 504 of the Rehabilitation Services Act, and in provisions of the Americans with Disabilities Act, are often overlooked within both mental health and housing systems and should be utilized as important tools for assisting people with psychiatric disabilities to meet their housing needs. (9) Education, information, and training in these protections are of critical importance to consumers and family members as well as to housing and mental health staff. (10) State and local mental health agencies should develop partnerships with housing finance and development agencies to increase housing access and supply. (11) State mental health agencies should support the development of knowledge and skills necessary for accessing mainstream housing resources. (12) Creative use of mainstream housing resources both new and existing (e.g., Community Development Block Grant, HOME funds), should be a priority of mental health and housing authorities. (13) The leadership of the state mental health agency must view rental assistance as part of a larger strategy designed to increase access to integrated housing. (14) Rental assistance activities should be developed in the context of an overall housing policy that supports a variety of activities designed to increase the availability of integrated housing. Helpful activities include assembling groups of stakeholders to assist in the development and oversight of state policy regarding housing and residential services. (Tennessee Department of Mental Health and Developmental Disabilities, 2010)

A recent study conducted by Dennis Culhane and colleagues and published by the Fannie Mae Foundation states conclusions that supportive housing, described as "permanent housing with attendant social services" has always been considered to be "prohibitively expensive" however, it is stated that this type of housing "…has emerged as a good investment because it is shown to substantially reduce the use of other publicly funded services." (Tennessee Department of Mental Health and Developmental Disabilities, 2010) It is stated that New York City "…established a comprehensive supportive housing program for homeless people with severe mental illness. A major study of the program calculated that long-term homeless people with severe mental illness used an average of $40,500 a year in public shelter, corrections, and health care services. For those placed in the permanent supportive housing program, the reduced use of acute care services nearly offset the costs of the supportive housing." (Tennessee Department of Mental Health and Developmental Disabilities, 2010) In fact, evaluations of other programs similar to these have discovered that retention rates for supportive housing programs are 80% and that these lead to "significant reductions in hospitalizations and shelter use." (Tennessee Department of Mental Health and Developmental Disabilities, 2010)

Evaluations of similar programs nationally have found that most supportive housing programs…