Background: Cannabis use is considered a component cause of psychotic illness, interacting with genetic and other environmental risk factors. Little is known, however, about these putative interactions. The present study investigated whether an urban environment plays a role in moderating the effects of adolescent cannabis use on psychosis risk.
Method: Prospective data (n=1923, aged 14–24 years at baseline) from the longitudinal population-based German Early Developmental Stages of Psychopathology cohort study were analysed. Urbanicity was assessed at baseline and defined as living in the city of Munich (1562 persons per km2; 4061 individuals per square mile) or in the rural surroundings (213 persons per km2; 553 individuals per square mile). Cannabis use and psychotic symptoms were assessed three times over a 10-year follow-up period using the Munich version of the Composite International Diagnostic Interview.
Results: Analyses revealed a significant interaction between cannabis and urbanicity [10.9% adjusted difference in risk, 95% confidence interval (CI) 3.2–18.6, p=0.005]. The effect of cannabis use on follow-up incident psychotic symptoms was much stronger in individuals who grew up in an urban environment (adjusted risk difference 6.8%, 95% CI 1.0–12.5, p=0.021) compared with individuals from rural surroundings (adjusted risk difference −4.1%, 95% CI −9.8 to 1.6, p=0.159). The statistical interaction was compatible with substantial underlying biological synergism.
Conclusions: Exposure to environmental influences associated with urban upbringing may increase vulnerability to the psychotomimetic effects of cannabis use later in life.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:26468 |
| Date | January 2011 |
| Creators | Kuepper, Rebecca, Van Os, Jim, Lieb, Roselind, Wittchen, Hans-Ulrich, Henquet, Cécile |
| Publisher | Cambridge University Press |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Source | Psychological Medicine, Bd. 41 (2011), Nr.10, S. 2121-2129, ISSN: 0033-2917 |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1017/S0033291711000511, 0033-2917 |
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