Early adolescent cannabis exposure and positive and negative dimensions of psychosis
N. C. Stefanis, Philippe Delespaul, Cécile Henquet, C. Bakoula, C. N. Stefanis, Jim van Os
Addiction October 1, 2004 DOI: 10.1111/j.1360-0443.2004.00806.x (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Cross-sectional survey Peer reviewed |
|---|---|
| Sample size | 3,500 |
| Population | Representative 19-year-olds in Greece |
| Measures | Community Assessment of Psychic Experiences |
| Topics | Cannabis |
| Key findings | Cannabis use was positively associated with both positive and negative psychosis dimensions, independent of each other and depression. First use before age 16 was associated with a much stronger effect than first use after age 15, independent of lifetime frequency. The association was not influenced by distress, suggesting self-medication is an unlikely explanation. |
Abstract
ABSTRACTAims To investigate the effect of exposure to cannabis early in adolescence on subclinical positive and negative symptoms of psychosis.Design Cross‐sectional survey in the context of an ongoing cohort study.Setting Government‐supported general population cohort study.Participants A total of 3500 representative 19‐year olds in Greece.Measurements Subjects filled in the 40‐item Community Assessment of Psychic Experiences, measuring subclinical positive (paranoia, hallucinations, grandiosity, first‐rank symptoms) and negative psychosis dimensions and depression. Drug use was also reported on.Findings Use of cannabis was associated positively with both positive and negative dimensions of psychosis, independent of each other, and of depression. An association between cannabis and depression disappeared after adjustment for the negative psychosis dimensions. First use of cannabis below age 16 years was associated with a much stronger effect than first use after age 15 years, independent of life‐time frequency of use. The association between cannabis and psychosis was not influenced by the distress associated with the experiences, indicating that self‐medication may be an unlikely explanation for the entire association between cannabis and psychosis.Conclusions These results add credence to the hypothesis that cannabis contributes to the population level of expression of psychosis. In particular, exposure early in adolescence may increase the risk for the subclinical positive and negative dimensions of psychosis, but not for depression.