Self-reported reasons for use of cannabis among youths at heightened clinical risk for psychosis

Abstract

Background: Cannabis use is prevalent among patients at clinical high risk (CHR) for schizophrenia and related psychotic disorders, despite its temporal association with increased psychotic-like symptoms. It is not known why CHR patients use cannabis despite these negative effects. The aims of this study were to assess the prevalence of cannabis use in CHR patients, their self-reported reasons for cannabis use, and the symptom correlates of these reasons for use. We hypothesized that as in schizophrenia, patients would endorse use of cannabis primarily for mood enhancement, and that this would be associated with anxiety and anhedonia in the cohort. Methods: A cohort of 115 CHR patients was assessed for cannabis use in the past 30 days. Among the 24 CHR patients (21%) who endorsed use, we evaluated their self-reported reasons for use, as well as their concurrent symptoms, including anhedonia, anxiety, and subthreshold positive symptoms, using the Structured Interview for Prodromal Syndromes/Scale of Prodromal Symptoms. Results: Among the 24 CHR patients who endorsed cannabis use in the past 30 days, the most commonly endorsed reason for use was “mood enhancement”, as hypothesized. Motivation for enhancement of mood with cannabis was associated at a trend level with trait anhedonia (r = 0.4, p = 0.08). Posthoc analyses showed anxiety was associated with selfreported “social” motives for cannabis use (r = 0.6, p = 0.003), which remained significant when corrected for multiple comparisons. Posthoc analyses also suggested motivation for “relief of symptoms” was unrelated to subthreshold psychotic symptoms (r = −0.2, p = 0.32). Conclusion: Adolescents and young adults at risk for schizophrenia report motivations for use of cannabis primarily for mood enhancement, a common motivation that has been endorsed by schizophrenia patients. This may be related to the difficulty of anticipating pleasure in activities other than using cannabis. At-risk youths may also be “self-medicating” anxiety in an effort to be more social, though seem unlikely to be “self-medicating” their psychotic-like experiences, which may be more a consequence of cannabis use rather than a cause. Understanding why at-risk patients use cannabis is key to psychological treatments aimed at reducing cannabis use in youths at heightened and imminent risk of psychosis onset.