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Mental disorders conferred risk for homicide

Individuals with any mental disorder were at an almost fivefold increased risk for homicidal death, according to recent study results.

“People with mental disorders may be at increased risk of homicidal death for several reasons, including a high prevalence of comorbid substance use, which is associated with violence,” the researchers wrote. “Irrespective of substance use, they also are more likely to live in high deprivation areas, which have higher homicide rates, be in closer contact with other mentally ill people, be less aware of their safety needs, or potentially be victimised because of perceptions that they are dangerous or vulnerable.”

Casey Crump, MD, PhD, a clinical assistant professor of medicine at Stanford University, and colleagues conducted a nationwide cohort study of all people aged 17 years or older living in Sweden on Jan. 1, 2001. The researchers examined the homicide rate during 8 years of follow-up and used regression analyses to determine the risks for homicidal death associated with mental disorders, which were identified through the Swedish outpatient and hospital registries.

 

Casey Crump

After adjusting for sociodemographic factors, the hazard ratio for homicidal death related to any mental disorder was 4.91 (95% CI, 3.99-6.03). The researchers found strong associations between homicidal death and mental illness irrespective of age, sex or other sociodemographic factors.

The risk for homicidal death was highest among those with substance use disorders (HR=9.37; 95% CI, 7.39-11.88), but there also were elevated risks for homicide associated with personality disorders (HR=3.21; 95% CI, 1.70-6.06), depression (HR=2.55; 95% CI, 1.70-3.83), anxiety disorders (HR=2.16; 95% CI, 1.32-3.52) and schizophrenia (HR=1.82; 95% CI, 0.85-3.86).

However, there was still an increased risk for homicidal death among mentally ill individuals who had no substance use disorders (HR=2.13; 95% CI, 1.52-2.99).

Crump and colleagues noted that the risk factors associated with homicidal death were similar to those linked to suicide.

“Interventions to reduce violent death among people with mental disorders should tackle risks of victimisation and homicidal death in addition to suicide and accidents,” they wrote.

Disclosure: The researchers report no relevant financial disclosures.