Cannabis use at a young age is associated with psychotic experiences

Rudolf Magnus Institute of Neuroscience, University Medical Centre Utrecht, Department of Psychiatry, The Netherlands.
Psychological Medicine (Impact Factor: 5.94). 10/2010; 41(6):1-10. DOI: 10.1017/S003329171000187X
Source: PubMed


BACKGROUND: Cannabis use is associated with psychosis and a range of subclinical psychiatric symptoms. The strength of this association depends on dosage and age at first use. The current study investigates whether level of cannabis exposure and starting age are associated with specific profiles of subclinical symptoms.MethodWe collected cross-sectional data from a young adult population sample by administering an online version of the Community Assessment of Psychic Experiences (CAPE). Cannabis exposure was quantified as the amount of Euros spent on cannabis per week and the age of initial cannabis use. The primary outcome measure was the odds ratio (OR) to belong to the highest 10% of scores on the total CAPE and the positive-, negative- and depressive symptom dimensions. RESULTS: In 17 698 adolescents (mean age 21.6, s.d.=4.2 years), cannabis use at age 12 years or younger was strongly associated with a top 10% score on psychotic experiences [OR 3.1, 95% confidence interval (CI) 2.1-4.3] and to a lesser degree with negative symptoms (OR 1.7, 95% CI 1.1-2.5). The OR of heavy users (>€25/week) for negative symptoms was 3.4 (95% CI 2.9-4.1), for psychotic experiences 3.0 (95% CI 2.4-3.6), and for depressive symptoms 2.8 (95% CI 2.3-3.3). CONCLUSIONS: Early start of cannabis use is strongly associated with subclinical psychotic symptoms and to a lesser degree with negative symptoms, while smoking high amounts of cannabis is associated with increased levels of all three symptom dimensions: psychotic, negative and depressive. These results support the hypothesis that the impact of cannabis use is age specific.

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Available from: Marco PM Boks, Jun 10, 2015
    • "The questionnaire has been used in genetic research (e.g., Stefanis et al., 2007), experimental research (e.g., Lincoln et al., 2010a), and studies that aim to elucidate the risk factors of schizophrenia, such as child abuse (e.g., DeRosse et al., 2014) or cannabis use (e.g., Schubart et al., 2011). Despite the CAPE's wide application, the validity of its original factor structure has not always been replicated. "
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