Do the Transmissible Liability Index (TLI) and Adolescent Cannabis Use Predict Paranoid and Schizotypal Symptoms at Young Adulthood?

Adolescent cannabis use and family history of substance use disorders (SUD) each independently predict paranoid and schizotypal personality traits in young adulthood, but preadolescent transmissible liability to SUD does not. The study followed 448 children of men with or without a lifetime SUD history from ages 10-12 to age 19. Cannabis use at age 16 and family SUD history were both linked to higher paranoid and schizotypal symptoms at age 19, with no interactive effect between liability and cannabis use. Paranoid and schizotypal symptoms displayed different dose-dependent sensitivities to cannabis exposure, suggesting distinct pathways not involving behavioral disinhibition.

Study at a glance

Abstract

Background: Adolescent cannabis use is an established risk factor for the development of psychosis, but the premorbid vulnerability factors and specificity versus generality of the psychotic symptom domains affected in cannabis-psychosis relationships remain incompletely understood. To improve our understanding of these relationships, we used longitudinal data to examine the individual and interactive effects of preadolescent transmissible liability to substance use disorders (SUD), measured via the transmissible liability index (TLI), and adolescent cannabis use on the development of two distinct psychotic symptom domains, paranoid and schizotypal personality traits in young adulthood. Methods: We performed secondary analysis of data from the Center for Education and Drug Abuse (CEDAR) study, which longitudinally assessed offspring of men with (N = 211) and without (N = 237) lifetime history of SUD at ages 10-12, and across adolescence as they transitioned to young adulthood. TLI scores were calculated at age 10-12, self-reported cannabis use was assessed at age 16, and paranoid and schizotypal symptoms were assessed at age 19. Results: Cannabis use at age 16 and family history of SUD were significantly associated with paranoid and schizotypal symptoms at age 19, but TLI scores were not. The interactive effect of TLI x cannabis use was also not significant. Paranoid and schizotypal symptoms showed different dose-dependent sensitivities to cannabis exposure at age 16. Conclusions: These findings indicate that adolescent cannabis use and family history of SUD differentially contribute to the development of paranoid and schizotypal personality traits through mechanisms that do not include behavioral disinhibition.