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Kraan T.,University of Amsterdam | Velthorst E.,University of Amsterdam | Velthorst E.,Mount Sinai School of Medicine | Smit F.,Trimbos Institute Netherlands Institute of Mental Health and Addiction | And 4 more authors.
Schizophrenia Research

Background: Childhood trauma and recent life-events have been related to psychotic disorders. The aim of the present study was to examine whether childhood trauma and recent life-events are significantly more prevalent in patients at Ultra High Risk (UHR) of developing a psychotic disorder compared to healthy controls. Method: A search of PsychInfo and Embase was conducted, relevant papers were reviewed, and three random-effects meta-analyses were performed. One meta-analysis assessed the prevalence rate of childhood trauma in UHR subjects and two meta-analyses were conducted to compare UHR subjects and healthy control subjects on the experience of childhood trauma and recent life-events. Results: We found 12 studies on the prevalence of (childhood) trauma in UHR populations and 4 studies on recent life-events in UHR populations. We performed a meta-analysis on 6 studies (of which trauma prevalence rates were available) on childhood trauma in UHR populations, yielding a mean prevalence rate of 86.8% (95% CI 77%-93%). Childhood trauma was significantly more prevalent in UHR subjects compared to healthy control groups (Random effects Hedges' g= 1.09; Z= 4.60, p< .001). In contrast to our hypothesis, life-event rates were significantly lower in UHR subjects compared to healthy controls (Random effects Hedges' g= - 0.53; Z= - 2.36, p< .02). Conclusions: Our meta-analytic results illustrate that childhood trauma is highly prevalent among UHR subjects and that childhood trauma is related to UHR status. These results are in line with studies on childhood trauma in psychotic populations. In contrast to studies on recent life-events in psychotic populations, our results show that recent life-events are not associated with UHR status. © 2014 Elsevier B.V. Source

Gieling M.,University Utrecht | Vollebergh W.,University Utrecht | Van Dorsselaer S.,Trimbos Institute Netherlands Institute of Mental Health and Addiction
Social Psychiatry and Psychiatric Epidemiology

Objective: The present study set out to examine the association between ethnic composition of school classes and prevalence of internalising and externalising problem behaviour among ethnic minority and majority students. Methods: Data were derived from the Dutch 2002 Health Behaviour in School-aged Children (HBSC) survey, a nationally representative cross-sectional study with a total of 5,730 adolescents, aged 11-18 and attending secondary school, of which 931 belong to ethnic minority groups. The data were analysed using a multilevel regression model. Results: The study revealed that, after taking individual characteristics like age, gender, educational level and family affluence into account, ethnic minority students on average report higher levels of externalising but not internalising problems. Ethnic density on the level of school classes modified this difference, as a negative association between the proportion ethnic minority students in class and externalising problem behaviour was found, but only for ethnic minority students. No effect of ethnic composition was found with respect to internalising problem behaviour. Conclusion: The data revealed that ethnic minority students report higher levels of externalising problem behaviour, but only in classes with a minority of ethnic minority students and not in classes with a culturally diverse composition. This points towards a possible beneficial effect of a more culturally diverse environment for minority students. Majority students appeared to be insensitive for the ethnic density effect. Future studies should investigate the role of the ethnic composition of the school class more in-depth. © The Author(s) 2009. Source

Brunt T.M.,Trimbos Institute Netherlands Institute of Mental Health and Addiction | van Amsterdam J.G.C.,National Institute of Public Health and the Environment RIVM | van Amsterdam J.G.C.,Amsterdam Institute for Addiction Research | van den Brink W.,University of Amsterdam | van den Brink W.,Amsterdam Institute for Addiction Research
Current Pharmaceutical Design

A growing body of evidence shows that gamma-hydroxybutyric acid (GHB) is an addictive substance. Its precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) show the same properties and may pose even more risks due to different pharmacoki-netics. There are indications that problematic GHB use is increasing in the European Union. This review investigates the existing literature on the neurochemistry of GHB and its precursors, their acute toxicity, addiction potential and withdrawal, the proposed molecular mechanism underlying addiction and the treatment of withdrawal and addiction. Current evidence shows that GHB and its precursors are highly addictive, both in humans and animals, probably through a GABAB receptor related mechanism. Severity of withdrawal symptoms can be considered as a medical emergency. Recent studies suggest that benzodiazepines are not very effective, showing a high treatment resistance, whereas detoxification with pharmaceutical GHB proved to be successful. However, relapse in GHB use is frequent and more research is warranted on relapse prevention. This might aid medical practitioners in the field and improve general understanding of the severity of addiction to GHB, GBL and 1,4-BD. © 2014 Bentham Science Publishers. Source

Van Der Gaag M.,VU University Amsterdam | Van Der Gaag M.,Parnassia Psychiatric Institute | Smit F.,VU University Amsterdam | Smit F.,Trimbos Institute Netherlands Institute of Mental Health and Addiction | And 7 more authors.
Schizophrenia Research

Over the last decade many studies were conducted to assess the feasibility of early detection of people at risk of developing psychosis and intervention to prevent or delay a first psychotic episode. Most of these studies were small and underpowered. A meta-analysis can demonstrate the effectiveness of the efforts to prevent or postpone a first episode of psychosis.A search conducted according the PRISMA guideline identified 10 studies reporting 12-month follow-up data on transition to psychosis, and 5 studies with follow-ups varying from 24 to 48. months. Both random and fixed effects meta-analyses were conducted.The quality of the studies varied from poor to excellent. Overall the risk reduction at 12. months was 54% (RR. = 0.463; 95% CI. = 0.33-0.64) with a Number Needed to Treat (NNT) of 9 (95% CI. = 6-15). Although the interventions differed, there was only mild heterogeneity and publication bias was small. All sub-analyses demonstrated effectiveness. Also 24 to 48-month follow-ups were associated with a risk reduction of 37% (RR. = .635; 95% CI. = 0.44-0.92) and a NNT of 12 (95% CI. = 7-59). Sensitivity analysis excluding the methodologically weakest study showed that the findings were robust.Early detection and intervention in people at ultra-high risk of developing psychosis can be successful to prevent or delay a first psychosis. Antipsychotic medication showed efficacy, but more trials are needed. Omega-3 fatty acid needs replication. Integrated psychological interventions need replication with more methodologically sound studies. The findings regarding CBT appear robust, but the 95% confidence interval is still wide. © 2013 Elsevier B.V. Source

Van Amsterdam J.,University of Amsterdam | Brunt T.,Trimbos Institute Netherlands Institute of Mental Health and Addiction | Van Den Brink W.,University of Amsterdam
Journal of Psychopharmacology

Cannabis use is associated with an increased risk of psychosis in vulnerable individuals. Cannabis containing high levels of the partial cannabinoid receptor subtype 1 (CB1) agonist tetrahydrocannabinol (THC) is associated with the induction of psychosis in susceptible subjects and with the development of schizophrenia, whereas the use of cannabis variants with relatively high levels of cannabidiol (CBD) is associated with fewer psychotic experiences. Synthetic cannabinoid receptor agonists (SCRAs) are full agonists and often more potent than THC. Moreover, in contrast to natural cannabis, SCRAs preparations contain no CBD so that these drugs may have a higher psychosis-inducing potential than cannabis. This paper reviews the general toxicity profile and the adverse effects of SCRAs with special emphasis on their psychosis-inducing risk. The review shows that, compared with the use of natural cannabis, the use of SCRAs may cause more frequent and more severe unwanted negative effects, especially in younger, inexperienced users. Psychosis and psychosis-like conditions seem to occur relatively often following the use of SCRAs, presumably due to their high potency and the absence of CBD in the preparations. Studies on the relative risk of SCRAs compared with natural cannabis to induce or evoke psychosis are urgently needed. © The Author(s) 2015. Source

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