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 …

van den Berg SM, Paap MC, Derks EM, Using multidimensional modeling to combine self-report symptoms with clinical judgment of schizotypy

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 …

Dekker N, Koeter M, Van Den Brink W, Craving for cannabis in patients with psychotic disorder, their non-affected siblings and healthy controls: psychometric analysis of the obsessive compulsive drug use scale

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 …

Klaassen RM, Heins M, Luteijn LB, van der Gaag M, van Beveren NJ, Depressive symptoms are associated with (sub)clinical psychotic symptoms in patients with non-affective psychotic disorder, siblings and healthy controls

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 …

Derks EM, Boks MP, Vermunt JK, The identification of family subtype based on the assessment of subclinical levels of psychosis in relatives

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, …

Derks EM, Vorstman JA, Ripke S, Kahn RS, , Ophoff RAInvestigation of the genetic association between quantitative measures of psychosis and schizophrenia: a polygenic risk score analysis

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 …

Gladwin TE, Derks EM, , Rietschel M, Mattheisen M, Breuer R, Schulze TG, Nöthen MM, Levinson D, Shi J, Gejman PV, Cichon S, Ophoff RASegment-wise genome-wide association analysis identifies a candidate region associated with schizophrenia in three independent samples

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, …

van der Werf M, Köhler S, Verkaaik M, Verhey F, van Os J, Cognitive functioning and age at onset in non-affective psychotic disorder

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, …

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, Mortensen PB, Demontis D, Hollegaard MV, van Winkel R, Kenis G, De Hert M, Réthelyi JM, Bitter I, Rubino IA, Golimbet V, Kiemeney LA, van den Berg LH, Franke B, Jönsson EG, Farmer A, Stefansson H, Stefansson K, Collier DAReplication study and meta-analysis in European samples supports association of the 3p21.1 locus with bipolar disorder

Intermediate phenotype analysis of patients, unaffected siblings, and healthy controls identifies VMAT2 as a candidate gene for psychotic disorder and neurocognition

Simons CJ, van Winkel R, Schizophr Bull 2013 Jul;39(4):848-56 PMID: 22532702 Abstract Psychotic disorders are associated with neurocognitive alterations that aggregate in unaffected family members, suggesting that genetic vulnerability to psychotic disorder impacts neurocognition. The aim of the present study was to investigate whether selected schizophrenia candidate single nucleotide polymorphisms (SNPs) are associated with (1) neurocognitive functioning across populations at …

Simons CJ, van Winkel R, Intermediate phenotype analysis of patients, unaffected siblings, and healthy controls identifies VMAT2 as a candidate gene for psychotic disorder and neurocognition

The association between social anhedonia, withdrawal and psychotic experiences in general and high-risk populations

Velthorst E, Meijer C, Schizophr. Res. 2012 Jul;138(2-3):290-4 PMID: 22484023 Abstract BACKGROUND: Social anhedonia (SA) and withdrawal are clinically relevant phenomena in schizophrenia. To examine the nature of the overlap between SA, withdrawal and positive symptoms, we investigated whether the co-occurrence of these phenotypes is more prominent in siblings of patients with a psychotic disorder compared to healthy controls, and …

Velthorst E, Meijer C, The association between social anhedonia, withdrawal and psychotic experiences in general and high-risk populations