Cannabis use linked to more severe psychosis, higher relapse risk, South African study finds

A South African study reveals a concerning link between cannabis use and more severe psychosis in individuals with schizophrenia and other psychotic disorders. The research, published in the South African Journal of Psychiatry, analyzed records of patients admitted to a psychiatric hospital between June 2018 and June 2020. The findings indicate that cannabis use is prevalent among people with these conditions, with 48.9% of patients being current users and 51.1% having used cannabis at some point in their lives.

The researchers caution that cannabis use alongside psychotic disorders can lead to more difficult recovery processes. People who use cannabis may experience earlier onset of symptoms, more severe symptoms, and poorer adherence to psychiatric medication. This can result in poorer functional outcomes, higher relapse rates, and longer hospital stays compared to non-users.

The study also highlights the potential negative impact on relationships, employment, and daily life, with some individuals facing homelessness, violence, or incarceration.

In South Africa, where cannabis use is common among people experiencing psychotic illness, the decriminalization of personal cannabis use adds another layer of complexity. The study notes that previous research has consistently found a connection between cannabis use and psychosis, suggesting that cannabis use can both increase the risk of developing psychosis and exacerbate symptoms in those already experiencing early psychotic symptoms.

The researchers emphasize that the relationship between cannabis use and psychosis is influenced by genetic and environmental factors. They also point to the growing concern surrounding high-potency cannabis, which has been linked to an increased risk of first-episode psychosis and subsequent schizophrenia. Previous South African studies have reported cannabis use among 37% to 68% of people with psychotic illnesses, with rates varying based on the population and setting.

However, these earlier studies were conducted before the decriminalization of personal cannabis use in the country.

For families supporting individuals with psychosis, the study underscores the importance of identifying cannabis use when a person receives psychiatric treatment. The researchers stress that cannabis use should not be viewed in isolation from a person's mental health, particularly when they have experienced psychotic symptoms or have required hospitalization multiple times.

The combination of cannabis use and psychotic illness can complicate treatment and recovery, highlighting the need for comprehensive care approaches that address both mental health and substance use.