Evidence linking mental health issues to violence is often met with a great deal of skepticism and is generally considered a myth. Some statistics have even found that people suffering from a mental illness are actually 10 times more susceptible to be a victim of a violent crime. A recent study conducted at the University of Oxford has found people diagnosed with depression are three times more likely to commit a violent crime.

According to the World Health Organization, more than 350 million people of every age group suffer from depression. It is also considered the leading cause of disability worldwide and a major contributor to the global burden of disease.

“One important finding was that the vast majority of depressed persons were not convicted of violent crimes, and that the rates reported are below those for schizophrenia and bipolar disorder, and considerably lower than for alcohol or drug abuse," Professor Seena Fazel, from the Department of Psychiatry at Oxford, said in a statement.

Fazel and his colleagues used a Swedish register that connects every person born in the country after 1932 to their parents and health care databases to compare medical records and conviction rates among 47,158 people in Sweden diagnosed with depression. Researchers confirmed that findings from this study would be applicable to other countries, considering Sweden’s violent crime and depression rates are similar to other Western countries.

People who had been diagnosed with depression were at a five to six times higher risk for self-harm compared to the general population. People struggling with depression were also twice as likely to be violent compared to their own siblings who had not been diagnosed with depression. The research team also identified family-related risk factors that may contribute to depressed people’s increased risk for violence, including shared generic heritage and mistreatment during childhood.

“Quite understandably, there is considerable concern about self-harm and suicide in depression,” Fazel added. “We demonstrate that the rates of violent crime are at least as high, but they don’t receive the same level of attention in clinical guidelines or mainstream clinical practice.”

A similar study conducted at the London School of Hygiene & Tropical Medicine has shown that the relationship between depression and violence could actually be a chicken-or-the-egg situation. Lead researcher Karen Devries found that symptoms of depression are highly common among women who have experienced intimate partner violence. Findings from this study were unique compared to others due to chronology. Longitudinal studies were split in showing that either depressed women were more susceptible to IPFor IPF increased women’s risk for IPF.

Source: Lichtenstein P, Goodwin G, Larsson H, Chang Z, Wolf A, Fazel S. Depression and violence: a Swedish population study. The Lancet. 2015.