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
    • "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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    ABSTRACT: Aim: This study examined the factorial and criterion validity of the Community Assessment of Psychic Experiences (CAPE). We compared the validity of the original three-dimensional model and a recently proposed multidimensional model, in which positive symptoms are subdivided into the subfactors hallucinations, bizarre experiences, paranoia, grandiosity and magical thinking and negative symptoms are subdivided into social withdrawal, affective flattening and avolition. Methods: Eleven community (n=934) and three patient samples (n=112) were combined and the proposed models were tested using confirmatory factor analysis. Criterion validity was calculated based on self-report measures for depression and paranoia as well as observer-based ratings for positive and negative symptoms. Results: The multidimensional model showed better relative quality (AIC, BIC) than the original three-dimensional model of the CAPE, but both models showed acceptable absolute model-fit (RMSEA, SRMR). The criterion validity was good for the positive symptom scales and negative symptom subfactors social withdrawal and affective flattening. Conclusion: Factorial validity was found for the three-dimensional and multidimensional model for the CAPE. The multidimensional model, however, shows better comparative fit and promising results in regard to criterion validity. Thus, we recommend a hierarchical multidimensional structure of positive and negative symptoms for future use of the CAPE.
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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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    ABSTRACT: In order to quantify the effectiveness of family interventions in preventing and reducing adolescent illicit drug use, we conducted a systematic review and meta-analysis of randomized controlled trials. We searched the Cochrane Database of Systematic Reviews, Educational Research Information Centre (ERIC), MEDLINE, Embase, and PsycINFO for studies published between 1995 and 2013. Results were described separately for different outcomes (marijuana vs. other illicit drugs) and intervention types (universal, selective, and indicated prevention). Meta-analyses were performed when data were sufficient (e.g., marijuana and other illicit drug initiation in universal samples), using random effect models. Otherwise, we provided narrative reviews (e.g., regarding selective and indicated prevention). Thirty-nine papers describing 22 RCTs were eligible for inclusion. Universal family interventions targeting parent-child dyads are likely to be effective in preventing (OR 0.72; 95 % CI 0.56, 0.94) and reducing adolescent marijuana use, but not in preventing other illicit drugs (OR 0.90; 95 % CI 0.60, 1.34). Among high-risk groups, there is no clear evidence for the effectiveness of family interventions in preventing and reducing illicit drug use and drug disorders. The three small RCTs among substance-(ab)using adolescents gave some indication that programs might reduce the frequency of illicit drug use. Family interventions targeting parent-child dyads are likely to be effective in preventing and reducing adolescent marijuana use in general populations, but no evidence for other illicit drug use was found. We underline the need to strengthen the evidence base with more trials, especially among at-risk populations.
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