Insight into cannabis use disorder in people with psychotic disorders

Background: Cannabis use is common in people with psychosis and is associated with poor outcomes.

Aims: To assess insight into cannabis use disorder, perceptions about how cannabis use influences mental health and the desire to change cannabis use among people with psychotic disorders.

Method: Adults with a psychotic disorder and comorbid cannabis use disorder were asked about the impact of cannabis use on their illness and their desire to change cannabis use. Cannabis use disorder was determined using DSM-5 criteria. Participants completed the Substance Use Awareness and Insight Scale.

Results: Sixty-two participants (mean age: 42 years; 95% male; 65% Black ethnicity; 85% severe DSM-5 cannabis use disorder) completed the study. The mean total Substance Use Awareness and Insight Scale score was 4.8 (s.d.: 2.1), with subdomain scores of 3.7 (s.d.: 2.8) for general illness awareness, 6.2 (s.d.: 2.8) for symptom attribution, 3.5 (s.d.: 2.9) for awareness of need for treatment and 5.6 (s.d.: 3.8) for awareness of negative consequences. Fifty-eight per cent said that cannabis use made their mental health 'better', whereas only 15% said it made it 'worse'; 27% reported that cannabis made their psychotic symptoms 'better', and 21% said it made them 'worse'. Nevertheless, more than half the sample (53%) said they wanted to reduce or stop using cannabis.

Conclusions: Many people with psychotic disorders have impaired insight into cannabis use disorder or believe that cannabis improves their mental health; these factors may contribute to persistent use in this population. Interventions that improve insight may help to address ambivalence and support those already wishing to reduce use.