The Relationship between Locus of Control and Psychotic Experiences: Moderating Effect of past-year cannabis use Frequency among Young Adult Lifetime cannabis Users

Abstract

Studies examining the relationship between locus of control (LoC; i.e., the extent to which individuals believe they have control over their lives) and psychotic symptoms in both clinical and non-clinical samples did not take cannabis use into account. Understanding the role of cannabis in this relationship is important to inform prevention efforts. To contribute to the field, this study aimed to test the hypothesis that past-year cannabis use frequency moderates the association between LoC and psychotic experiences (PEs). This study has a cross-sectional design. A self-administered online questionnaire was adopted to collect data from participants, using the snowball sampling method. The questionnaire included a section on sociodemographic information, and the three following measures: the Prodromal Questionnaire-Brief, the Internal–External Locus of Control Short Scale-4, and a 7-point single-item scale to assess past-year cannabis use frequency. A total of 475 young adult lifetime cannabis users from Tunisia (age range 18–35 years, with a mean age of 26.87 ± 3.90 years and 44.2% females), with no history of psychotic disorders and/or antipsychotics intake, were included. After controlling for potential confounders (age, marital status, education level, living arrangement, region of living, tobacco and alcohol use, household crowding index, and personal history of psychiatric illness), moderation analyses showed that past-year cannabis use moderated the association between external LoC and PEs (beta = .10; t = 2.29; p = .022; 95% CI 01; .18). At moderate (beta = .64; p < .001) and high (beta = .74; p < .001) levels of cannabis use, higher external LoC was significantly associated with more severe PEs. No moderating role was found for internal LoC. Findings suggest that among young adults who have a more externally oriented LoC, moderate- to high-frequency past-year cannabis users are more likely to exhibit greater PEs. Therefore, more attention should be directed towards this group of individuals in the context of early intervention programs. Future longitudinal studies in different cultural contexts and more representative samples are still required to confirm the present findings.