Article

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

ABSTRACT

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
    • "First-degree relatives were invited through the patients. The CannabisQuest study is a crosssectional study that included adolescents and young adults from the general population (Schubart et al. 2011; Vinkers et al. 2013). Participants completed an online questionnaire and were subsequently assessed by a psychiatric interview and neuropsychological tests at the UMC Utrecht. "
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    ABSTRACT: Background: Schizophrenia is associated with lower intelligence and poor educational performance relative to the general population. This is, to a lesser degree, also found in first-degree relatives of schizophrenia patients. It is unclear whether bipolar disorder I (BD-I) patients and their relatives have similar lower intellectual and educational performance as that observed in schizophrenia. Method: This cross-sectional study investigated intelligence and educational performance in two outpatient samples [494 BD-I patients, 952 schizophrenia spectrum (SCZ) patients], 2231 relatives of BD-I and SCZ patients, 1104 healthy controls and 100 control siblings. Mixed-effects and regression models were used to compare groups on intelligence and educational performance. Results: BD-I patients were more likely to have completed the highest level of education (odds ratio 1.88, 95% confidence interval 1.66-2.70) despite having a lower IQ compared to controls (β = -9.09, s.e. = 1.27, p < 0.001). In contrast, SCZ patients showed both a lower IQ (β = -15.31, s.e. = 0.86, p < 0.001) and lower educational levels compared to controls. Siblings of both patient groups had significantly lower IQ than control siblings, but did not differ on educational performance. IQ scores did not differ between BD-I parents and SCZ parents, but BD-I parents had completed higher educational levels. Conclusions: Although BD-I patients had a lower IQ than controls, they were more likely to have completed the highest level of education. This contrasts with SCZ patients, who showed both intellectual and educational deficits compared to healthy controls. Since relatives of BD-I patients did not demonstrate superior educational performance, our data suggest that high educational performance may be a distinctive feature of bipolar disorder patients.
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    • "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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    • "Adolescent illicit drug use is common in Western society, with early initiation and frequent use being associated with increased risks of academic failure (Fergusson et al. 2007) and mental health problems, e.g., depression (de Graaf et al. 2010) and psychosis (Henquet et al. 2005; Schubart et al. 2011; Smit et al. 2004; Van Os et al. 2002). Almost a third (29 %) of European 15-to 16-year-olds have used cannabis (Hibell et al. 2012). "
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