If the tabloid press and many movies were anything to go by, one would assume that anyone with a psychotic disorder was crazed murderer, with evil voices telling them to kill innocent people. This is of course a sensationalised view, and in actual fact, although many people believe that those with mental disorders are more likely to commit violent acts, results of research which indicates this are subject to conflicting interpretations, due to methodological, and other, issues. Some question forensic psychologists have still and are currently been trying to clarify in this area are; whether or not those with major mental disorders are any more likely to commit violent acts than those without, if psychosis is a risk factor, and how to predict which individuals in the mentally disordered population are at more at risk of becoming violent.
In a study of mentally disordered patients by Stedman et al (1998) comparisons were made with the general population, this yielded results which indicated that the abuse of substances was a key factor in violence in the mentally disordered sample. When he compared these results to the general population there was no distinction between prevalence of violence among the general population and the patents where substance abuse was not involved. Where there was substance abuse however, there was a marked increase in violence in both samples, with patients showing more violence in the weeks following discharge from psychiatric care. Most of the violence was shown to be directed at family members and known people. This refutes the notion that patents with mental disorders are any more of a danger to society in general than others who commit violent crimes.
Bonta, Law and Hanson (1998) also proposed from their findings, that risk factors for the mentally ill committing violent crimes are very similar to those for the general population.
One of the next issues in this area is in the classification of the types of mental disorder. The disorders that fall into the category of psychotic disorders are schizophrenia, bi-polar disorder (formerly known as manic depression) schizoaffective disorder, schizophreniform disorder and substance induced psychosis. The way in which the psychiatrists and psychologists define mental disorders differs greatly, and this in itself can pose a problem for the individual with a mental disorder. Psychiatric diagnosis seeks to classify individuals with mental disorders, whereas much research in psychology points to a need to remove such labels on the basis that it can serve as not much more than to stigmatise individuals (Pilgrim, 2000). Most of the classification is based on observation and expert opinion, and little of it is based on scientific, hypothesis-based research.
In order to review the literature on violence and psychotic disorders, it is necessary to outline the symptoms. Using the classification system of the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM), mental illness is categorised into five broad areas of psychiatric diagnosis. The disorders mentioned above, fall in to DSM-IV. The presence of two or more of the following symptoms over a period of a month...