Researchers warn that cannabis use among individuals suffering from schizophrenia and other psychotic disorders may contribute to a more complex and destructive course of the illness. They note that cannabis consumers may experience earlier onset of symptoms, a more severe disease progression, and an increased risk of relapse.
The study, published in the South African Journal of Psychiatry, analyzed medical records of patients hospitalized in a psychiatric hospital. It was found that cannabis is widely used among individuals diagnosed with conditions belonging to the schizophrenia spectrum and other psychotic disorders.
According to the findings, 48.9% of patients were current cannabis users, and 51.1% had used it at some point in their lives. This data is particularly important for South Africa, where cannabis use was prevalent among people with psychotic illnesses, and where personal cannabis use was decriminalized before the study was conducted.
The research warns that combining cannabis use with a psychotic disorder can complicate the recovery process. The researchers emphasize: 'Co-use of cannabis with schizophrenia and other psychotic disorders is associated with a more severe course of the illness.'
In the opinion of the researchers, people with psychotic disorders who use cannabis may exhibit symptoms at a younger age and experience more serious manifestations than those who do not use this substance. Furthermore, they may have difficulty taking psychiatric medications regularly, which hinders condition management.
It was noted that 'cannabis users with psychosis have an earlier onset of illness, increased symptom severity, poorer adherence to psychiatric medication regimens, worse functional outcomes, higher rates of relapse, and longer hospital stays compared to non-users.'
The impact of this condition extends beyond the individual. Researchers observed that people experiencing psychosis while using cannabis may face challenges in relationships, employment, and daily life. In some cases, consequences can include homelessness, violence, and incarceration, placing an additional burden on caring families.
The study examined 370 clinical records of patients aged 13 and older who were hospitalized in a psychiatric hospital between June 2018 and June 2020. Most patients were young: about 66.2% were between 16 and 34 years old, and 70.5% were male. It was also found that 93.9% of patients were unmarried, 88% had only primary education, and 89.2% were unemployed.
For many patients, psychosis was not a new phenomenon; the median duration of the psychotic illness was three years, with 48% having been hospitalized three or more times. The high rate of cannabis use among patients raised concerns for the researchers, as previous studies had repeatedly indicated a link between cannabis and psychotic disorders. 'Thus, we note a high comorbidity between cannabis use and psychosis, and that the dual diagnosis of cannabis use and psychotic disorder is a poor prognostic factor.'
Bidirectional Relationship
Researchers also highlighted the complex relationship between cannabis and psychosis. While cannabis use may increase the risk of developing psychosis, individuals already experiencing early symptoms of psychosis may also turn to cannabis. 'Psychosis and prodromal symptoms of schizophrenia may also exacerbate cannabis use.'
This means the link is not necessarily that cannabis causes psychosis in every person. Researchers suggested that genetic and environmental factors may contribute to this relationship. High-concentration cannabis is of particular concern, as recent investigations show it increases the risk of first episode psychosis and subsequent schizophrenia. 'Recent studies show that use of high-concentration cannabis increases the risk of PEP and subsequent schizophrenia.'
Researchers noted that unusually high rates of cannabis use among people with psychotic disorders had previously been reported in South Africa. Previous South African studies recorded cannabis use among 37% and 68% of people with psychotic illnesses, depending on the population and conditions. In KwaZulu-Natal, one of the earlier studies showed cannabis use among 68.8% of adolescents with psychotic disorders, and another showed a prevalence of 35% among adults with psychotic illness. However, the authors pointed out that these studies were conducted approximately ten years ago and before the decriminalization of personal cannabis use in South Africa. 'Factors related to comorbidity in the African context may differ from others.'
Researchers added that cultural and environmental differences, as well as cannabis availability and changes in cannabis legislation, can influence usage patterns.
What These Findings Mean for Families
For families supporting someone with psychosis, the data underscores the importance of identifying cannabis use during mental illness treatment. Cannabis use should not be viewed in isolation from a person's mental health, especially if they have experienced psychotic symptoms or required multiple hospitalizations. Researchers particularly emphasized that the combination of cannabis use and a psychotic disorder can significantly complicate treatment and recovery. 'The literature suggests a high prevalence of co-occurring cannabis use among individuals with psychotic disorders.'