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Contains fulltext : 117698.pdf (publisher's version ) (Open Access), This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness - "I feel sleepy during the first hours at school" - appeared to predict both school grades and self-reported school performance. Sleep quality on the other hand - as a measure of (un)interrupted sleep and/or problems falling asleep or waking up - predicted parent-reported school performance. Self- and parent-reported school performance correlated only moderately with school grades. So it turns out that the measures used to measure either sleep or school performance impacts whether or not a relation is found. Further research on sleep and school performance should take this into account. The findings do underscore the notion that sleep in adolescence can be important for learning. They are compatible with the hypothesis that a reduced sleep quality can give rise to sleepiness in the first hours at school which results in lower school performance. This notion could have applied value in counseling adolescents and their parents in changing adolescents' sleep behavior.

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Contains fulltext : 184873.pdf (publisher's version ) (Open Access), This study examined differences between boys and girls regarding efficiency of information processing in early adolescence. Three hundred and six healthy adolescents (50.3% boys) in grade 7 and 9 (aged 13 and 15, respectively) performed a coding task based on over-learned symbols. An age effect was revealed as subjects in grade 9 performed better than subjects in grade 7. Main effects for sex were found in the advantage of girls. The 25% best-performing students comprised twice as many girls as boys. The opposite pattern was found for the worst performing 25%. In addition, a main effect was found for educational track in favor of the highest track. No interaction effects were found. School grades did not explain additional variance in LDST performance. This indicates that cognitive performance is relatively independent from school performance. Student characteristics like age, sex, and education level were more important for efficiency of information processing than school performance. The findings imply that after age 13, efficiency of information processing is still developing and that girls outperform boys in this respect. The findings provide new information on the mechanisms underlying boy-girl differences in scholastic performance.

Objectives. This study explores associations between metacognitive beliefs and beliefs about voices in patients with severe auditory verbal hallucinations, and their hypothesized relationship with levels of depression and anxiety. Furthermore, it was hypothesized that metacognitive beliefs are better able to explain differences in levels of depression and anxiety, than beliefs about voices. Design. Cross-sectional data were obtained from baseline measurements of a randomized controlled trial. All patients (N = 77) met the criteria for a DSM-IV diagnosis within the schizophrenia spectrum. A correlation analysis was conducted to explore the associations between metacognitive beliefs and beliefs about voices. Regression analysis was performed to test the second hypothesis. Method. Metacognitive beliefs were measured using the MCQ-30. Beliefs about voices were measured using the BAVQ-R. Furthermore, the Beck Depression Inventory-II and the Beck Anxiety Inventory were applied to measure depression and anxiety. All analyses were a priori controlled for gender and level of education. Results. Significant associations were found between negative beliefs about voices and negative metacognitive beliefs. One of the metacognitive beliefs, that is, perceived uncontrollability and danger of thinking, proved to be a key variable in explaining differences in levels of depression and anxiety and seemed to have greater explanatory value than all of the beliefs about voices when analysed simultaneously. Conclusions. The results offer modest support to models emphasizing the fact that metacognitive beliefs are a core feature in the development and maintenance of depression and anxiety in patients with severe auditory verbal hallucinations. © 2012 The British Psychological Society.

This study examined differences between boys and girls regarding efficiency of information processing in early adolescence. Three hundred and six healthy adolescents (50.3% boys) in grade 7 and 9 (aged 13 and 15, respectively) performed a coding task based on over-learned symbols. An age effect was revealed as subjects in grade 9 performed better than subjects in grade 7. Main effects for sex were found in the advantage of girls. The 25% best-performing students comprised twice as many girls as boys. The opposite pattern was found for the worst performing 25%. In addition, a main effect was found for educational track in favor of the highest track. No interaction effects were found. School grades did not explain additional variance in LDST performance. This indicates that cognitive performance is relatively independent from school performance. Student characteristics like age, sex, and education level were more important for efficiency of information processing than school performance. The findings imply that after age 13, efficiency of information processing is still developing and that girls outperform boys in this respect. The findings provide new information on the mechanisms underlying boy-girl differences in scholastic performance. © 2013 Dekker, Krabbendam, Aben, de Groot andJolles.

Background Bullying victimization may be linked to psychosis but only self-report measures of victimization have been used so far. This study aimed (a) to investigate the differential associations of peer-nominated versus self-reported victim status with non-clinical psychotic experiences in a sample of young adolescents, and (b) to examine whether different types of self-reported victimization predict non-clinical psychotic experiences in these adolescents. Method A combination of standard self-report and peer nomination procedures was used to assess victimization. The sample (n = 724) was divided into four groups (exclusively self-reported victims, self- and peer-reported victims, exclusively peer-reported victims, and non-victims) to test for a group effect on non-clinical psychotic experiences. The relationship between types of victimization and non-clinical psychotic experiences was examined by a regression analysis. Results Self-reported victims, along with self- and peer-reported victims, scored higher than peer-reported victims and non-victims on non-clinical psychotic experiences. Self-reports of direct relational, indirect relational and physical victimization significantly improved the prediction of non-clinical psychotic experiences whereas verbal and possession-directed victimization had no significant predictive value. Conclusions The relationship between victimization and non-clinical psychotic experiences is only present for self-reported victimization, possibly indicative of an interpretation bias. The observed discrepancy between self-report and peer-report highlights the importance of implementing a combination of both measures for future research. Copyright © Cambridge University Press 2012.

Background: Semantic network abnormalities in patients with psychotic disorder were examined using associative prime-target relations with two stimulus asynchronies (SOAs: -250 ms and -500 ms) to assess the time course of automatic and more controlled processes of semantic priming. To investigate whether an aberrant semantic network system is part of the familial liability for psychosis, healthy siblings of patients with psychotic disorder were additionally examined. The N400 event-related brain potential (ERP) was used as a probe of semantic processing.Method: Twenty-two patients with psychotic disorder, twenty siblings of patients with psychotic disorder and twenty controls participated in a lexical decision task and ERPs were recorded to target words that were associatively, indirectly or not related to their preceding prime word.Results: Associative priming of the N400 amplitude was found across all participants and both SOAs, but no between-group differences were found for the N400 amplitude (both SOAs). The Group x Condition interaction of the indirect priming N400 latency of the three groups was just short of statistical significance (F2,59=2.7, p = .077). Patients showed an increased indirect priming effect of the N400 latency only at short SOA, with decreased latency of the indirectly related compared to the unrelated condition, while controls did not show an indirect priming N400 latency effect No between-group differences in N400 latency of indirect priming were found at the long SOA. Only a trend towards a Group x Condition interaction of the indirect priming N400 latency between the sibling and the controls was found, but without a main effect of indirect priming in the sibling group.Conclusion: These preliminary results support the assumption of a hyperactive semantic network in patients with psychotic disorder, which develops under automatic processes and decreases with more controlled processes, but does not represent clear tr

Psychotic illness is a disorder of social interaction unique to humans. However, up to now research has failed to pin down the exact determinants of the complex and interactive processes associated with the development of trust and reciprocity in psychosis. Utilizing a novel multi-round version of an interactive trust game experiment, we show that patients with psychosis and healthy relatives with a heightened risk for the illness exhibit lower baseline levels of trust compared with healthy controls. This effect partly overlapped with a reduced general intelligence. Furthermore, patients were unable to modify their trusting behaviour neither in response to information about the general trustworthiness of their interaction partner, nor in response to their partners' specific direct behavioural feedback. Relatives, in contrast, modified their trusting behaviour towards similar levels as healthy subjects in response to both. The results show that behavioural flexibility in response to socially relevant information is a critical determinant of success in the instantiation and maintenance of social relationships. A lack thereof may drive social dysfunction and the progression from subclinical symptoms to a full-blown psychosis. This offers a testable mechanistic hypothesis for progression from prodrome to psychotic illness, and may provide a therapeutic avenue to grapple the psychotic symptoms of social dysfunction.

In this study, the authors aimed to examine 4 domains of executive functioning in adults with attention-deficit/hyperactivity disorder (ADHD)-namely interference control, concept shifting, verbal fluency, and verbal working memory. Four groups of participants were included: (a) adults diagnosed with ADHD (ADHD(-): n = 20), (b) adults diagnosed with both ADHD and 1 or more comorbid disorder(s) (ADHD(+): n = 22), (c) adults referred for ADHD because of ADHD symptomatology but not diagnosed as such (non-ADHD; n = 34), and (d) healthy controls (n = 136). ADHD-related deficits (independent of comorbidity) were revealed for concept shifting and verbal working memory. In addition. the ADHD(+) and non-ADHD groups displayed deficits in terms of general processing speed. Given that these deficits were not found in the ADHD(-) group, the authors contend that these deficits are likely attributable to comorbidity rather than ADHD itself. Contrary to the authors' expectations, these findings do not correspond with the cognitive subtype hypothesis.

Contains fulltext : 56017.pdf (publisher's version ) (Closed access), The aim of the current study was to replicate the finding that cognitive impairments are not or inversely associated with sensitivity to stress in a sample of 25 patients diagnosed with psychotic disorder. The results indicated that impairments in performance on the Trailmaking Test and the Stroop Color Word Test were inversely associated with sensitivity to stress in daily life, whereas impairment in a subtest of the Behavioral Assessment of Dysexecutive Syndrome (BADS) was not associated with stress-sensitivity. The data thus show that in some instances cognitive functioning is not, and in other instances is inversely associated with momentary sensitivity to stress. Cognitive impairment and affective reactivity thus appear to be independent or mutually exclusive mechanisms in psychosis, suggesting competing causal pathways.

Contains fulltext : 48314.pdf (publisher's version ) (Open Access), OBJECTIVE: To investigate the relation between cannabis use and psychotic symptoms in individuals with above average predisposition for psychosis who first used cannabis during adolescence. DESIGN: Analysis of prospective data from a population based sample. Assessment of substance use, predisposition for psychosis, and psychotic symptoms was based on standardised personal interviews at baseline and at follow up four years later. PARTICIPANTS: 2437 young people (aged 14 to 24 years) with and without predisposition for psychosis. MAIN OUTCOME MEASURE: Psychotic symptoms at follow up as a function of cannabis use and predisposition for psychosis at baseline. RESULTS: After adjustment for age, sex, socioeconomic status, urbanicity, childhood trauma, predisposition for psychosis at baseline, and use of other drugs, tobacco, and alcohol, cannabis use at baseline increased the cumulative incidence of psychotic symptoms at follow up four years later (adjusted odds ratio 1.67, 95% confidence interval 1.13 to 2.46). The effect of cannabis use was much stronger in those with any predisposition for psychosis at baseline (23.8% adjusted difference in risk, 95% confidence interval 7.9 to 39.7, P = 0.003) than in those without (5.6%, 0.4 to 10.8, P = 0.033). The risk difference in the "predisposition" group was significantly greater than the risk difference in the "no predisposition" group (test for interaction 18.2%, 1.6 to 34.8, P = 0.032). There was a dose-response relation with increasing frequency of cannabis use. Predisposition for psychosis at baseline did not significantly predict cannabis use four years later (adjusted odds ratio 1.42, 95% confidence interval 0.88 to 2.31). CONCLUSION: Cannabis use moderately increases the risk of psychotic symptoms in young people but has a much stronger effect in those with evidence of predisposition for psychosis.

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Item does not contain fulltext, To examine the hypothesis that individuals from the general population who report childhood abuse are at increased risk of developing positive psychotic symptoms. Method: Data were derived from a general population sample of 4045 subjects aged 18–64 years. First ever onset of positive psychotic symptoms at 2-year follow-up were assessed using the Composite International Diagnostic Interview and additional clinical interviews if necessary. Childhood abuse was assessed at baseline. Results: Baseline reported childhood abuse predicted development of positive psychotic symptoms associated with need for care [odds ratio (OR) = 11.5, 95% CI 2.6–51.6]. This association remained after adjustment for demographic variables, reported risk factors and presence of any lifetime psychiatric diagnosis at baseline (OR = 7.3, 95% CI 1.1–49.0). Conclusion: The results suggest that early childhood trauma increases the risk for positive psychotic symptoms. This finding fits well with recent models that suggest that early adversities may lead to psychological and biological changes that increase psychosis vulnerability.

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Item does not contain fulltext, Background: Little is known about sex differences in psychosis beyond the borders of clinical disorder. Methods: A general population sample of 7076 subjects was assessed using the Composite International Diagnostic Interview, in order to explore sex differences in the prevalence of any positive and negative symptoms of psychosis, and to examine to what degree any differences could be explained by differences in level of affective symptoms. Results: Male sex was associated with higher prevalence of negative symptoms (OR=1.6, 95% CI=1.0, 2.5), independent of differences in affective symptoms and presence of DSM-III-R psychotic disorder. Women had higher rates of positive psychotic experiences (OR=0.8, 95% CI=0.7, 0.9), but this difference disappeared after adjustment for depressive symptoms (adjusted OR=1.2, 95% CI=0.9, 1.5). Conclusion: The sex differences in psychopathology that are seen in schizophrenia are expressed beyond the clinical phenotype, suggesting sex-dependent continuous and normal variation of several psychosis dimensions. The higher rates of positive psychotic experiences seen in women may be secondary to differences in the rate of affective symptoms.