Acute cannabis use causes increased psychotomimetic experiences in individuals prone to psychosis
O. Mason, C. J. A. Morgan, S. K. Dhiman, A. Patel, N. Parti, Hv Curran
Psychological Medicine June 1, 2009 DOI: 10.1017/s0033291708004741 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 284 |
| Population | Cannabis users and non-using controls |
| Measures | Psychotomimetic States Inventory (PSI), Schizotypal Personality Questionnaire (SPQ) |
| Topics | Cannabis |
| Key findings | Acute cannabis use reliably increased psychotomimetic symptoms, and highly psychosis-prone individuals experienced enhanced psychotomimetic states compared to those low in psychosis proneness. |
Abstract
BackgroundEpidemiological evidence suggests a link between cannabis use and psychosis. A variety of factors have been proposed to mediate an individual's vulnerability to the harmful effects of the drug, one of which is their psychosis proneness. We hypothesized that highly psychosis-prone individuals would report more marked psychotic experiences under the acute influence of cannabis.MethodA group of cannabis users (n=140) completed the Psychotomimetic States Inventory (PSI) once while acutely intoxicated and again when free of cannabis. A control group (n=144) completed the PSI on two parallel test days. All participants also completed a drug history and the Schizotypal Personality Questionnaire (SPQ). Highly psychosis-prone individuals from both groups were then compared with individuals scoring low on psychosis proneness by taking those in each group scoring above and below the upper and lower quartiles using norms for the SPQ.ResultsSmoking cannabis in a naturalistic setting reliably induced marked increases in psychotomimetic symptoms. Consistent with predictions, highly psychosis-prone individuals experienced enhanced psychotomimetic states following acute cannabis use.ConclusionsThese findings suggest that an individual's response to acute cannabis and their psychosis-proneness scores are related and both may be markers of vulnerability to the harmful effects of this drug.