Homelessness and mental illness often go hand in hand. Studies have shown high rates of mental health issues among homeless populations. So what mental disorders are most prevalent among the homeless? Here we’ll examine the data on the most common mental illnesses affecting homeless individuals.
Summary of Key Findings
Research has found the following key points regarding mental illness among the homeless:
- Mental illness is disproportionately common among the homeless. Around 20-25% of homeless individuals live with a severe mental illness like schizophrenia, bipolar disorder or severe depression.
- The most common diagnoses are substance abuse disorders, personality disorders, and depression. These affect 30-60% of homeless individuals.
- Schizophrenia affects an estimated 10-20% of homeless adults. This is around 4-8 times higher than the general population rate of 1-2%.
- Bipolar disorder affects around 10% of homeless adults, compared to 2-4% of the general public.
- Post-traumatic stress disorder (PTSD) and anxiety disorders also have high prevalence among the homeless, ranging from 15-35% in studies.
- Co-occurring mental health and substance abuse disorders are extremely common, affecting up to 75% of homeless with mental illness.
- The rates of most disorders are higher among women and veterans within the homeless population.
Mental illness rates are disproportionately high among homeless populations
It is clear from decades of research that rates of mental illness are much higher within homeless communities compared to the general population. The majority of homeless individuals are affected by some form of mental health disorder during their lives.
According to a review by Fazel et al. (2008), studies conducted in Western countries have generally found that around one-third of homeless people have alcohol dependence issues and around one-fifth have some form of severe mental illness. Severe mental illnesses include diagnoses like schizophrenia, bipolar disorder and severe major depression.
In their systematic review of 29 studies, Fazel and colleagues found that across surveys the rate of alcohol dependence ranged from 8.5% to 58.5%, with most studies finding between 30% and 50%. For drug dependence the rates ranged from 4.7% to 54.2%.
The rates of psychotic illnesses and major depression varied more widely between studies but were consistently elevated compared to the general population. For psychosis the prevalence ranged from 2.8% to 42.3%, with most surveys reporting 15-25%. For major depression the rates ranged from 0% to 40%, with most finding between 10-20%.
Overall the studies clearly showed around one-fifth to a quarter of homeless individuals suffering from a severe mental illness, ranging from psychosis to severe mood disorders. Let’s look more closely at the rates of specific disorders.
Schizophrenia and bipolar disorder are 4-8 times more common among the homeless
Schizophrenia spectrum disorders and bipolar disorder stand out as having particularly high rates within the homeless population compared to the general public.
For schizophrenia, most studies reviewed by Fazel et al. found prevalence between 10-15% in Western countries. The overall rate calculated from pooled data was 11.4%. This compares to around just 1-2% prevalence in the total population.
So in summary: schizophrenia is around 4-8 times more common among homeless adults than the overall population. Schizophrenia is a severe psychotic disorder characterized by delusions, hallucinations and disorganized thinking and behavior. It is associated with high disability and impairment.
Similarly, the pooled prevalence of bipolar disorder from the studies was 11.4%. Again this is highly elevated above the general population prevalence which is estimated at around 2-4%.
So bipolar disorder is around 3 times more common among the homeless. The condition causes mood episodes of severe depression and mania. Like schizophrenia, bipolar is very disabling without proper treatment.
The reasons for the high rates of psychotic disorders among the homeless are likely complex. Contributing factors may include the inability to maintain treatment and instability disrupting medication, self-care and finances.
Substance abuse disorders are the most prevalent issue faced by 30-60% of homeless
In addition to serious mental illness, substance abuse issues are rampant among homeless populations. Fazel et al.’s review found alcohol dependence was the most common single disorder, affecting anywhere from 8.5% to 58.5% of the homeless across surveys, with most finding rates of 30-50%.
Reported rates of drug dependence ranged from 4.7% to 54.2% with most studies identifying prevalence between 10-25%. Taken together, the combined rates of alcohol or drug dependence are estimated at approximately 37% on average. However prevalence likely ranges closer to 50-60% in many homeless communities.
The National Coalition for the Homeless (2009) similarly summarized that 38% of homeless people are dependent on alcohol while 26% abuse other drugs. They stated substance abuse is the single largest cause of homelessness for single adults.
The high rates of substance abuse disorders reflect the intersections between mental illness, trauma, poverty and homelessness. Drugs and alcohol may be used as coping mechanisms which then contribute to detriments in health and stability. Support for recovery is an essential need for homeless populations.
Personality disorders affect around a quarter of homeless adults
Another common mental health diagnosis among the homeless is personality disorders, which affect around 23% on average according to Fazel et al.’s study review. The prevalence ranged between 2-71% across surveys, reflecting the diversity of methodologies.
Personality disorders include conditions like borderline personality disorder and antisocial personality disorder. They involve pervasive patterns of unstable functioning, moods and behavior. People with personality disorders often have trouble maintaining stable housing, employment and relationships.
The stressors and marginalization of homelessness are likely to exacerbate personality disorder symptoms. However, there may also be overlap with developmental trauma disorders which can manifest in similar ways. Overall poor access to mental healthcare contributes to high rates of personality disorders going undiagnosed and untreated.
PTSD and anxiety disorders affect around 15-35% of homeless
Post-traumatic stress disorder (PTSD) and other anxiety disorders have also been found to disproportionately impact homeless adults.
Among samples of homeless men and women, PTSD rates have been found ranging from around 15% up to 34% according to various studies (Fazel et al., Tsai et al.). This is estimated at 2-3 times higher than the lifetime PTSD prevalence of 6.8% within the broader population.
Anxiety disorder rates have been found to be around 21-29% among homeless adults based on limited research (Rezansoff et al., Fazel et al.). Generalized anxiety disorder and social phobia appear to be particularly common. Again anxiety disorder prevalence is approximately double that of the general public.
The traumatic experiences that often lead to homelessness, in conjunction with the ongoing stresses of poverty and survival struggles, contribute to this higher vulnerability to PTSD and anxiety issues.
Major depression affects around 10-25% of homeless adults
Major depressive disorder is another leading mental health issue facing homeless communities. Fazel et al.’s analysis found prevalence ranging between 0-40% across studies, with most data clustering around 10-25%.
By comparison, 6.7% of US adults experience major depressive disorder each year. Lifetime prevalence is around 16%. So like other conditions, rates of clinical depression are estimated to be around 1.5 to 3 times higher among the homeless.
Depression is often triggered and exacerbated by extremely difficult life events and circumstances. Navigating life without stable housing can provoke immense chronic stress and hopelessness linked to depression vulnerability.
Women and veterans show particularly high mental illness rates
Within overall homeless populations, certain groups show disproportionately high rates of mental illness.
Studies have consistently found women experience higher rates of most psychiatric conditions compared to homeless men. For example, Fazel et al. reported 29.6% of homeless women had psychotic disorders versus 11.3% of men. Rates of depression and PTSD are also elevated for homeless women based on multiple studies.
Likewise military veterans make up a large proportion of homeless individuals, due to factors including PTSD, substance abuse and lack of support networks. According to the VA (2013), veteran homelessness is associated with high rates of mental health issues, with PTSD being particularly common.
So women and veterans experiencing homelessness are especially likely to be struggling with untreated mental illness amidst inadequate healthcare access and resources.
Co-occurring disorders are the norm
Within the homeless population, mental illnesses rarely occur in isolation. Co-occurring mental health and substance abuse disorders are extremely common, along with physical health issues.
Fazel et al. reported that in surveys of those with psychotic disorders such as schizophrenia, approximately half also had substance abuse issues. For those with alcohol dependence, rates of psychotic and personality disorders reached around 25%.
According to the Substance Abuse and Mental Health Services Administration (SAMHSA), among people experiencing homelessness:
- Around two-thirds have a substance abuse disorder
- Over three-quarters have a mental disorder
- One-third have both a substance abuse and mental health disorder
So for the vast majority of homeless individuals with mental illness, complex co-occurring issues are the norm rather than the exception. This highlights the need for integrated treatment that addresses both mental health and substance abuse issues simultaneously.
Causes of high mental illness prevalence
There are a range of reasons why mental illness is so much more common among populations affected by homelessness compared to the general public.
Mental illness can contribute to loss of housing – Severe conditions like schizophrenia, bipolar disorder and major depression can make it difficult to maintain housing and employment without adequate treatment and support networks.
Homelessness can worsen mental illness – The stress and trauma of living without stable housing exacerbates preexisting mental health and substance abuse issues. Lack of healthcare access also prevents treatment.
Overlapping risk factors – Risk factors like poverty, childhood trauma, foster care involvement, family instability and imprisonment intersect with risks for homelessness as well as mental illness.
Flawed support systems – Homeless individuals end up concentrated in certain areas due to a lack of affordable housing and mental healthcare options. Supports are often underfunded and fragmented.
In summary, mental illness increases vulnerability to homelessness while homelessness in turn precipitates worsening mental health problems. Underlying societal issues also perpetuate the cycle of illness, instability and poverty.
Barriers to mental healthcare access among the homeless
Despite disproportionately high psychiatric disorder prevalence, homeless populations face major barriers to accessing mental health treatment and support.
The National Healthcare for the Homeless Council (2019) summarizes the following obstacles:
- Practical struggles – Difficulty getting to appointments, lack of transport, problems storing medication.
- Instability – Frequent moves between temporary accommodations disrupts care.
- Competing priorities – Obtaining food, shelter and safety takes precedence over health concerns.
- Distrust – Negative treatment experiences reduce likelihood of seeking further help.
- Complex needs – Co-occurring issues make coordinating effective treatment extremely challenging.
- Eligibility restrictions – Lack of health insurance prevents services access in the US.
Homeless individuals with mental illness are caught in a vicious cycle of increased needs and decreased access. Developing more accessible, integrated and proactive services is essential to breaking this cycle.
Strategies and recommendations
Given the extremely high prevalence of mental illness among the homeless coupled with barriers to treatment access, how can this crisis be addressed?
Experts recommend a multi-pronged public health approach focused on prevention, early intervention and creating robust treatment systems tailored to the needs of the homeless.
The US Interagency Council on Homelessness (USICH) suggests the following strategies based on current evidence:
- Increase affordable housing – This provides a stable base that enables addressing health and social needs.
- Address financial insecurity through approaches like case management, benefit enrollment assistance and job training programs.
- Integrate healthcare services – e.g. joint mental health and primary care clinics tailored for the homeless.
- Prioritize early intervention – Identify and treat mental illness as early as possible to improve long-term outcomes.
- Provide assertive outreach through street psychiatry and medical teams.
- Train providers in care approaches adapted for homeless populations.
- Peer support programs – employing previously homeless individuals to engage clients.
A collaborative, evidence-based public health approach across housing, healthcare, community, government and social service sectors is required to drive meaningful progress on this issue.
Conclusion
Research conclusively shows that mental illness is disproportionately common among homeless populations compared to the general public. The most common diagnoses include substance use disorders, personality disorders, PTSD, depression and psychotic disorders like schizophrenia and bipolar.
Rates of most mental illnesses are around twice as high among the homeless versus the total population. Schizophrenia and bipolar disorder are 4-8 times more prevalent. Co-occurring psychiatric and substance abuse issues affect the majority.
Mental illness is both a contributor to homelessness as well as an outcome. To improve outcomes, integrated treatment, early intervention and expanded housing and income support are needed alongside addressing wider societal risk factors.