People with mental illnesses are overrepresented in jail and prison populations in the United States relative to the general population. There are three times more seriously mentally ill people in jails and prisons than in hospitals in the United States. Scholars discuss many different causes of this overrepresentation, including the deinstitutionalization of mentally ill individuals in the mid-twentieth century, inadequate community treatment resources, and the criminalization of mental illness itself. The majority of prisons in the United States employ a psychiatrist and a psychologist. There is a consensus that mentally ill offenders have comparable rates of recidivism to non-mentally ill offenders. Mentally ill people experience solitary confinement at disproportionate rates and are more vulnerable to its adverse psychological effects. Twenty-five states have laws addressing the emergency detention of the mentally ill within jails, and the United States Supreme Court has upheld the right of inmates to mental health treatment.
Prevalence
There is a broad scholarly consensus that mentally ill individuals are overrepresented within the jail and prison populations of the United States. In a 2010 study, researchers concluded that, based on statistics from sources including the Bureau of Justice Statistics and the U.S. Department of Health and Human Services, there are currently three times more seriously mentally ill people in jails and prisons than in hospitals in the United States, with the ratio being nearly ten to one in Arizona and Nevada. "Serious mental illness" is defined here as schizophrenia, bipolar disorder, or major depression. Further, they found that 16% of the jail and prison population in the U.S. has a serious mental illness (compared to 6.4% in 1983), although this statistic does not reflect differences among individual states. For example, in North Dakota, they found that a person with a serious mental illness is equally likely to be in prison or jail versus a hospital. In contrast, in states such as Arizona, Nevada, and Texas, the imbalance is much more severe. Finally, they noted that a 1991 survey by the National Alliance for the Mentally Ill concluded that jail and/or prison are part of the life experiences of forty percent of these mentally ill individuals. In addition to mood and anxiety disorders, other psychopathologies have also been found in the US Prison System. Antisocial personality disorder is found in less than 6% of the general American population, but seems to be found in anywhere between 12% and 64% of prison samples. Estimates of borderline personality disorder seem to make up around 1% to 2% of the general public, compared to 12% to 30% within prisons. Personality disorders, especially in the inmate population, are often found to be comorbid with other disorders.
A separate research study, The Prevalence of Mental Illness among Inmates in a Rural State, noted that national statistics like those previously mentioned primarily pull data from urban jails and prisons. To investigate possible differences in rural areas, researchers interviewed a random sample of inmates in both jails and prisons in a rural northeastern state. They found that in this rural setting, there was little evidence of high rates of mental illness within jails, "suggesting the criminalization of mental illness may not be as evident in rural settings as urban areas." However, high rates of serious mental illness were found among rural prison inmates.
A 2017 report issued by the Bureau of Justice Statistics used self-reported survey data from inmates to assess the prevalence of mental health problems among prisoners and jail inmates. They found that 14% of prisoners and 25% of jail inmates had experienced serious psychological distress in the past 30 days, compared to 5% of the general population. In addition, 37% of prisoners and 44% of jail inmates had a history of mental health problems.