Obsessive-compulsive symptoms in patients with schizophrenia: a naturalistic cross-sectional study comparing treatment with clozapine, olanzapine, risperidone, and no antipsychotics in 543 patients

Scheltema Beduin AA, Swets M, Machielsen M, Korver N, J Clin Psychiatry 2012 Nov;73(11):1395-402 PMID: 23218156 Abstract OBJECTIVE: To compare the prevalence of obsessive-compulsive symptoms (OCS) in a population of patients with schizophrenia taking clozapine, olanzapine, or risperidone or taking no antipsychotic medication. METHOD: Baseline data of the Genetic Risk and Outcome of Psychosis study were collected between April 2005 …

Using multidimensional modeling to combine self-report symptoms with clinical judgment of schizotypy

van den Berg SM, Paap MC, Derks EM, Psychiatry Res 2013 Mar;206(1):75-80 PMID: 23021911 Abstract This study investigated psychometric properties of two widely used instruments to measure subclinical levels of psychosis, the Community Assessment of Psychic Experiences (CAPE) and the Structured Interview for Schizotypy-Revised (SIS-R), and aimed to enhance measurements through the use of multidimensional measurement models. Data were collected …

Craving for cannabis in patients with psychotic disorder, their non-affected siblings and healthy controls: psychometric analysis of the obsessive compulsive drug use scale

Dekker N, Koeter M, Van Den Brink W, Int J Methods Psychiatr Res 2012 Dec;21(4):286-300 PMID: 22961922 Abstract Cannabis use is more common in individuals with non-affective psychotic disorder and their siblings compared to healthy controls. As cannabis use is associated with a greater risk to develop psychotic disorder and an adverse outcome in those who already developed psychosis, it …

Depressive symptoms are associated with (sub)clinical psychotic symptoms in patients with non-affective psychotic disorder, siblings and healthy controls

Klaassen RM, Heins M, Luteijn LB, van der Gaag M, van Beveren NJ, Psychol Med 2013 Apr;43(4):747-56 PMID: 22804999 Abstract BACKGROUND: Depression is a clinically relevant dimension, associated with both positive and negative symptoms, in patients with schizophrenia. However, in siblings it is unknown whether depression is associated with subclinical positive and negative symptoms. Method Depressive symptoms and their association …

The identification of family subtype based on the assessment of subclinical levels of psychosis in relatives

Derks EM, Boks MP, Vermunt JK, BMC Psychiatry 2012;12:71 PMID: 22759464 Abstract BACKGROUND: Schizophrenia is a complex psychiatric disorder characterized by high phenotypic heterogeneity. Previous studies have distinguished between familial and sporadic forms of schizophrenia and have suggested clinical differentiation between patients and relatives from sporadic and multiplex families. We will introduce a more refined method to distinguish between family …

Investigation of the genetic association between quantitative measures of psychosis and schizophrenia: a polygenic risk score analysis

Derks EM, Vorstman JA, Ripke S, Kahn RS, , Ophoff RA PLoS ONE 2012;7(6):e37852 PMID: 22761660 Abstract The presence of subclinical levels of psychosis in the general population may imply that schizophrenia is the extreme expression of more or less continuously distributed traits in the population. In a previous study, we identified five quantitative measures of schizophrenia (positive, negative, disorganisation, …

Segment-wise genome-wide association analysis identifies a candidate region associated with schizophrenia in three independent samples

Gladwin TE, Derks EM, , Rietschel M, Mattheisen M, Breuer R, Schulze TG, Nöthen MM, Levinson D, Shi J, Gejman PV, Cichon S, Ophoff RA PLoS ONE 2012;7(6):e38828 PMID: 22723893 Abstract Recent studies suggest that variation in complex disorders (e.g., schizophrenia) is explained by a large number of genetic variants with small effect size (Odds Ratio ≈ 1.05-1.1). The statistical …

Cognitive functioning and age at onset in non-affective psychotic disorder

van der Werf M, Köhler S, Verkaaik M, Verhey F, van Os J, Acta Psychiatr Scand 2012 Oct;126(4):274-81 PMID: 22582732 Abstract OBJECTIVE: Age at psychosis onset has been related to variability in cognitive functioning, but its effect may be mediated by demographic and clinical factors. The aim of the current study was to study the contribution of age at onset, …

Replication study and meta-analysis in European samples supports association of the 3p21.1 locus with bipolar disorder

Vassos E, Steinberg S, Cichon S, Breen G, Sigurdsson E, Andreassen OA, Djurovic S, Morken G, Grigoroiu-Serbanescu M, Diaconu CC, Czerski PM, Hauser J, Babadjanova G, Abramova LI, Mühleisen TW, Nöthen MM, Rietschel M, McGuffin P, St Clair D, Gustafsson O, Melle I, Pietiläinen OP, Ruggeri M, Tosato S, Werge T, Ophoff RA, , Rujescu D, Børglum AD, Mors O, …