Genetic Risk and Outcome of Psychosis (GROUP), a multi-site longitudinal cohort study focused on gene-environment interaction: objectives, sample characteristics, recruitment and assessment methods

Korver N, Quee PJ, Boos HB, Simons CJ, de Haan L, Int J Methods Psychiatr Res 2012 Sep;21(3):205-21 PMID: 22419500 Abstract OBJECTIVE: A longitudinal focus on gene-environment vulnerability and resilience in both patients, their unaffected family members and non-related controls offers the opportunity to elucidate etiological and pathogenetic factors influencing the onset and course of psychotic disorders. The current paper …

Social cognition and quality of life in schizophrenia

Maat A, Fett AK, Derks E, Schizophr. Res. 2012 May;137(1-3):212-8 PMID: 22406280 Abstract Schizophrenia is associated with poor quality of life (QOL). Whereas the effects of neurocognitive deficits and psychopathology on QOL of schizophrenia patients have recently been elucidated, little is known about social cognitive deficits in this regard. This study investigated the influence of social cognition on QOL in …

Clinical response to antipsychotic drug treatment: association study of polymorphisms in six candidate genes

Vehof J, Burger H, Wilffert B, Al Hadithy A, Alizadeh BZ, Snieder H, Eur Neuropsychopharmacol 2012 Sep;22(9):625-31 PMID: 22386772 Abstract Pharmacogenetic studies have demonstrated significant associations between several candidate genes (DRD2, DRD3, 5HTR2A and 5HTR2C, COMT and MTHFR) and antipsychotic drug response. The present study investigates the effect of nine polymorphisms in these genes for an association with antipsychotic treatment …

The validity of the DSM-IV diagnostic classification system of non-affective psychoses

Korver-Nieberg N, Quee PJ, Boos HB, Simons CJ, Aust N Z J Psychiatry 2011 Dec;45(12):1061-8 PMID: 22026404 Abstract OBJECTIVE: The schizophrenia and other non-affective disorders categories listed in the DSM-IV, are currently under revision for the development of the fifth edition. The aim of the present study is to demonstrate the validity of these categories by investigating possible differences between …

Cognitive alterations in patients with non-affective psychotic disorder and their unaffected siblings and parents

Meijer J, Simons CJ, Quee PJ, Verweij K, Acta Psychiatr Scand 2012 Jan;125(1):66-76 PMID: 22013907 Abstract OBJECTIVE: The purpose of this study was to examine a range of cognitive measures as candidate phenotypic liability markers for psychosis in a uniquely large sample of patients with psychosis, their unaffected relatives and control subjects. METHOD: Patients with non-affective psychosis (n = 1093), …

Genome-wide association study identifies five new schizophrenia loci

Nat. Genet. 2011 Oct;43(10):969-76 PMID: 21926974 Abstract We examined the role of common genetic variation in schizophrenia in a genome-wide association study of substantial size: a stage 1 discovery sample of 21,856 individuals of European ancestry and a stage 2 replication sample of 29,839 independent subjects. The combined stage 1 and 2 analysis yielded genome-wide significant associations with schizophrenia for …

Cannabis and cognitive performance in psychosis: a cross-sectional study in patients with non-affective psychotic illness and their unaffected siblings

Meijer JH, Dekker N, Koeter MW, Quee PJ, van Beveren NJ, Meijer CJ, Psychol Med 2012 Apr;42(4):705-16 PMID: 21899795 Abstract BACKGROUND: The relationship between cannabis use and cognitive functioning in patients with psychosis has yielded contradictory findings. In individuals at genetic high risk for psychosis, information is sparse. The aim of this study was to assess the association between recency …

AKT1 moderation of cannabis-induced cognitive alterations in psychotic disorder

van Winkel R, van Beveren NJ, Simons C, Neuropsychopharmacology 2011 Nov;36(12):2529-37 PMID: 21775978 Abstract Genetic variation in AKT1 may be associated with sensitivity to the psychotomimetic effects of cannabis as well as with increased risk for psychotic disorder following cannabis use. Investigation of the effect of this interaction on relevant intermediate phenotypes for psychosis, such as cognition, may help to …

Differences in craving for cannabis between schizophrenia patients using risperidone, olanzapine or clozapine

Machielsen M, Beduin AS, Dekker N, , Kahn RS, Linszen DH, van Os J, Wiersma D, Bruggeman R, Cahn W, de Haan L, Krabbendam L, Myin-Germeys I J. Psychopharmacol. (Oxford) 2012 Jan;26(1):189-95 PMID: 21768161 Abstract Substance abuse and psychotic disorders have a high rate of comorbidity. Both disorders are associated with changes in the dopaminergic transmission in the mesocorticolimbic pathways …