The relationship between psychiatric illness and criminality has been the topic of intense debate and scrutiny in recent past in light of multiple mass shootings in the United States.  While the renewed focus and media attention on the importance of mental health in the aftermath of such tragedies is a positive development, the relationship between mental illness and criminality is too often conflated.

The popular belief is that people with mental illness are more prone to commit acts of violence and aggression. The public perception of psychiatric patients as dangerous individuals is often rooted in the portrayal of criminals in the media as “crazy” individuals.  A large body of data suggests otherwise. People with mental illness are more likely to be a victim of violent crime than the perpetrator.[1] This bias extends all the way to the criminal justice system, where persons with mental illness get treated as criminals, arrested, charged, and jailed for a longer time in jail compared to the general population.[2]

An essential element that plays into the false equivocation of psychiatric illness and criminality is the incorrect labeling of all criminals as persons with mental illness. The society at large views behavior and conduct problems as a symptom of a psychological disorder, which has led to the false public perception that equates criminality with psychiatric illness. The high levels of reported mental illness in jail and prison populations is primarily due to false labeling of criminals as having a psychiatric illness. These figures are not always based on thorough medical and psychiatric evaluation and diagnosis, but rather as a result of social factors.[3]

Anti-Social Personality Disorder (ASPD) is one such diagnosis that is widely and arbitrarily applied to many in the prison populations. As a result, there is a debate as to whether ASPD is even a psychiatric illness or just a societal moral judgment. The label is increasingly used to paint criminals as victims of psychiatric illness.[4] Thus, it is imperative for clinicians to ensure that diagnoses of personality disorders such as APSD are applied only when characteristic traits appear in childhood and adolescence, to not let criminals use the cover of psychiatric diagnoses to evade criminal punishment. 

People with mental illness are arrested and sent to prison in disproportionate numbers,[5] often due to a lack of awareness and resources in handling these individuals. The police often arrest these individuals for petty crimes such as jaywalking or wandering behavior as a preventive law and order measure.[5]  According to one study, 12 percent of adult psychiatric patients receiving treatment in the San Diego County health system had prior incarcerations, while 28 percent of Connecticut residents treated for schizophrenia and bipolar disorder had been arrested or detained.

The closure of state psychiatric hospitals which began with the deinstitutionalization drive in 1960 forced many psychiatric patients on the streets, forced to fend for themselves.[6] As a result, these patients came into contact with the police and the courts more often. The situation is exacerbated by a lack of training and staffing in the court system, potentially accounting for persons with mental illness comprising an ever-larger fraction of the jail and prison population. Many of the symptoms of psychiatric illnesses are behaviors considered antisocial or criminal such as wandering behavior.[7] The result has been the false perception of a causal relationship between psychiatric illness and criminality.

Certain psychiatric conditions do increase a person’s risk of committing a crime.  Research suggests that patients with mental illness may be more prone to violence if they do not receive adequate treatment,[8] are actively experiencing delusions, or have long-standing paranoia.[9] Such patients are often under the influence of their psychiatric illness such as command hallucinations.  Other comorbidities include conditions such as substance use disorder,[10] unemployment, homelessness, and secondary effects of mental illness such as cognitive impairment, compound the risk of committing a violent crime.

The most important and independent risk factor for criminality and violence among individuals with mental illness is a long-term substance use disorder.[10]  In patients with a major psychiatric illness, comorbid substance use disorder, there is a four-fold increase in the risk of committing a crime or violence.[11] Studies have shown that the rise in violent crime committed by individuals with mental illness, may entirely be accounted for with a history of alcohol and/or drug use.[11] 

Individuals with a severe mental illness that fall through the cracks or for one reason or another are non-adherent to treatment are particularly at higher risk of committing grave acts of violence.  Untreated profound mental illness is particularly significant in cases of homicide—the zenith of the criminal spectrum, and such illness is even more significant for mass murders of strangers. Still, these cases are a smaller proportion to senseless acts of violence committed by criminals who act out of sheer criminal intent.

Many individuals with mental illness face an uphill battle when trying to access mental health treatment. Many individuals do not receive the appropriate and timely treatment needed. Budget overruns and cuts in funding for public health and mental health in many cities further put people with mental illness in situations where they are involved in criminal activity.  Further complicating the picture is the lack of mental health treatment facilities. Despite greater awareness and effort to increase access to mental health treatment facilities, mental hospital beds per capita in the U.S. are lower than they have been since the 1850s.

A far-sighted national mental health policy with expanded availability and access to treatment, while costly in the short run, could be a cost-effective and sensible approach. By some estimates, a ninety-day treatment in a mental hospital might avoid 10-year imprisonment of an individual with mental illness. Expanded availability and access to mental health treatment would provide significant savings to society and crime victims. More importantly, it would improve a person with mental illness' quality of life and transform these individuals into productive members of society.

The link between psychiatric illness and criminality is complex and has profound societal implications. There is a great need for in-depth research and imaginative solutions for access and availability to mental health treatment. Currently, there is scant evidence to suggest that mental illness can independently predict criminal behavior. On the contrary, there is ample evidence that shows that persons with mental illness are far more likely to be the victim of violent crime rather than the perpetrator.