The public debate on violent crime usually assumes that violence in the mentally ill is a direct result of the perpetrator’s illness.
However, it has been unclear if the violence is due to the bipolar disorder per se, or caused by other aspects of the individual’s personality or lifestyle.
The new study, carried out by researchers at Karolinska Institutet and Oxford University, is presented in the scientific journal Archives of General Psychiatry.
Researchers compared the rate of violent crime in over 3,700 patients with bipolar disorder cared for in Swedish hospitals between 1973 and 2004 with that of 37,000 control individuals from the general public.
Twenty-one percent of patients with bipolar disorder and a concurrent diagnosis of severe substance abuse (alcohol or illegal drugs) were convicted of violent crimes, compared to five percent of those with bipolar disorder but without substance abuse, and three percent among general public control individuals.
The differences remained when accounting for age, gender, immigrant background, socioeconomic status, and whether the most recent presentation of the bipolar disorder was manic or depressed.
“Interestingly, this concurs with our group’s previous findings in schizophrenia, another serious psychiatric disorder, which found that individuals with schizophrenia are not more violent than members of the general public, provided there is no substance abuse,” says professor Niklas Långström, head of the Centre for Violence Prevention at Karolinska Institutet.
According to the researchers, the findings support the need for initiatives to prevent, identify and treat substance abuse when fighting violent crime. Additionally, Långström hopes that the results will help challenge overly simplistic explanations of the causes of violent crime.
“Unwarranted fear and stigmatization of mental illness increases the alienation of people with psychiatric disorder and makes them less inclined to seek the care they need,” Långström comments.
Source: Karolinska Institutet