Mentally Disordered Offenders

Crime is neither mental disorder nor necessarily evidence of such disorder. It is a misconception that all criminals are "sick," especially those who commit apparently senseless crimes or particularly serious crimes such as murder or rape. The concepts of crime and of mental disorder should be kept distinct. Crime is a violation of the criminal law, whereas mental disorder refers to behavior that is usually marked by some type of lack of the general capacity for rationality and accompanying distress or dysfunction. Conduct resulting from mental disorder may or may not be criminal and people with mental disorder may or may not be legally responsible for the behavior that mental disorder produces; criminal behavior, by contrast, is often highly rational. Thus, some crime is the product of mental disorder, but to consider all crime as a manifestation of such disorder would tend both to eliminate any sensible boundaries to the concept of mental disorder and to play havoc with generally accepted notions of morality and accountability.

The criminal behavior of people with mental disorders is difficult to estimate with precision because reliable data are hard to obtain. Many mentally disordered persons and many criminal acts never come to the attention of public authorities. Older studies of the issue, although suggestive, suffered from serious methodological flaws. Based on recent community-based studies that examine all criminal behavior, whether or not an offender is arrested and convicted, we can cautiously estimate that, in general, people with major mental disorders, such as schizophrenia or severe depression, are not at greater risk for criminal behavior than people without disorder. Drug use is much more closely correlated with criminal behavior than is mental disorder. People with and without major mental disorders who abuse illegal drugs and alcohol are equally and far more likely to engage in crime than people who do not use drugs, but people with mental disorders are about seven times more likely to abuse drugs and alcohol than people without disorders. Thus, although drug use independently accounts for more crime than does major mental disorder, the prevalence of criminal behavior among people with mental disorder may be greater because they are at much greater risk of drug use. People with less severe mental disorders, such as personality disorders, are at even greater risk for criminal behavior if they use illegal drugs and alcohol than people with major mental disorders or people without disorders.

The non-substance-related mental disorders that seem to have the strongest relation to crime are antisocial personality disorder (APD) and psychopathy, both of which are personality disorders. People with these disorders are generally in touch with reality and therefore are responsible for their behavior. APD is widely recognized as a mental disorder by its inclusion in the fourth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), but its classification as a mental disorder is problematic. The criteria for APD, for example, are largely persistent, serious antisocial behaviors and do not include cognitive or affective psychopathology. These diagnostic criteria virtually guarantee that APD will be found to a great degree among offenders, but such criteria offer little reason per se to consider the condition a disorder. Psychopathy is also frequent among prisoners. Psychopathy is not an officially recognized diagnostic category in DSM-IV, but there are good data to validate the disorder and it is used by many clinicians. The condition is marked by a wide range of psychopathology, including extreme egocentricity and lack of the capacity to experience empathy and guilt, and many psychopaths violate the law. The criteria for psychopathy are more readily considered psychopathological than antisocial behavior alone, but many claim that psychopathy is simply a label for people we dislike and fear rather than a genuine disorder. There is substantial but imperfect overlap between psychopathy and APD: many people who engage in persistent, serious antisocial behavior are not psychopaths, and many psychopaths are able to avoid persistent, serious antisocial behavior.

Although older data indicated that prisoners had higher rates of mental disorder, including major mental disorders, than the population at large, more recent data on the rate of mental disorder among prisoners—clearly only a subset of people who commit crimes—indicates that convicted offenders appear to be no more mentally disordered than nonoffenders. Approximately 20 to 35 percent of the national population actively suffers from some form of mental disorder or has suffered from mental disorder at some time during their lives, a proportion that is almost identical in prison populations. The proportion of prisoners who suffer from major mental disorders is relatively small, much as it is in the population at large. Recent evidence indicates that about 16 percent of state prisoners suffer from a current disorder and almost one-third reported a current or past condition. State prison inmates with a mental condition are more likely than other inmates to be incarcerated for a violent offense, to have been under the influence of alcohol or drugs at the time of the offense, and more likely to have been homeless in the year prior to arrest. The data about prisoners may not be representative of the proportion of offenders who suffer from disorders for at least two reasons. Offenders with mental disorders may be in general less competent and more likely to be caught, and some offenders with disorders may be diverted to the mental health system.

The generally low rate of severe mental disorders among prisoners is reflected in the small percentage of felony defendants (probably less than 10%) for whom the question of incompetence to stand trial is raised and in the even smaller percentage (approximately 1–2%, although with substantial variance among jurisdictions) of those who raise the insanity defense. Defendants are rarely found incompetent to stand trial or not guilty by reason of insanity unless they are or have been suffering from a major mental disorder and seem grossly out of touch with reality.

It is a matter of common knowledge that the prison environment is highly stressful, particularly in ways that may tend to predispose persons to develop mental disorders. Inmates lack the usual range of stimuli; they are alienated from normal familial, affectionate, and sexual relationships and social supports; and they often are fearful for their safety. Consequently, it is predictable that some prisoners who were previously free of mental disorder will become seriously disordered while incarcerated.