A recent study published in the Journal of Clinical Psychopharmacology, found no association between lifetime cannabis use and impulsive violent behaviour among subjects with schizophrenic spectrum disorders.
A combined Italian and Canadian research team set out to investigate if there was any evidence to support the claim that there is an association between lifetime cannabis use disorder, and severe violence in patients with schizophrenia spectrum disorders from a high-security hospital.
Researchers used a cross-sectional representative study involving 124 patients with schizophrenia who had all been admitted to a high-security hospital. Their past violent behaviour (VB) was assessed using various methods including the History of Aggressive Behavior Form-Subject of the MacArthur Violence Risk Assessment Study, and their impulsivity was assessed using the Psychopathy Checklist. The patient’s substance abuse history was analyzed using the Diagnostic and Statistical Manual of Mental Disorders.
In the published findings the researchers found that violent and nonviolent patients showed a similar prevalence of cannabis use disorder, whereas alcohol and cocaine disorders were more prevalent amongst violent patients.
They also found no association between those with cannabis use disorder and impulsivity, alcohol use disorder however was heavily correlated to impulsive thoughts.
Researchers showed with confidence that alcohol use disorder, unlike cannabis and cocaine use disorders, “was a factor associated with violence”.
The researchers state that their findings show that both cannabis and alcohol are largely abused and co-abused by patients with psychotic illnesses who have a propensity for violence. However, the data shows that it is only alcohol that is associated with impulsive and violent behaviour.
The premise that cannabis can cause its users to become violent, especially those who suffer from mental health issues such as schizophrenia and psychosis based illnesses, is an often-cited argument against loosening cannabis restrictions.
The view has been repeated many times, an example being the Fox News anchor Tucker Carlson using this argument to link the violence caused by a mass shooter in Ohio USA in 2019 to cannabis use. Carlson linked this and other violent acts to the perpetrators’ use of cannabis, even though the Ohio shooter also had Xanax, cocaine and alcohol present in his system.