van der Meer FJ, Meijer JH, Meijer CJ, van den Brink W, Velthorst E Psychol Med 2013 Nov;:1-11 PMID: 24267407 Abstract BACKGROUND: Little is known about the effect of stimulant use (amphetamines, cocaine, ecstasy) on cognitive functioning in schizophrenia patients. The current study examined (1) whether recency and frequency of stimulant use is associated with cognitive functioning and (2) whether …
Evidence that transition from health to psychotic disorder can be traced to semi-ubiquitous environmental effects operating against background genetic risk
van Nierop M, Janssens M, , Bruggeman R, Cahn W, de Haan L, Kahn RS, Meijer CJ, Myin-Germeys I, van Os J, Wiersma D PLoS ONE 2013;8(11):e76690 PMID: 24223116 Abstract BACKGROUND: In order to assess the importance of environmental and genetic risk on transition from health to psychotic disorder, a prospective study of individuals at average (n = 462) and …
The association between intelligence scores and family history of psychiatric disorder in schizophrenia patients, their siblings and healthy controls
Verweij KH, Derks EM, PLoS ONE 2013;8(10):e77215 PMID: 24130858 Abstract BACKGROUND: The degree of intellectual impairment in schizophrenia patients and their relatives has been suggested to be associated with the degree of familial loading for schizophrenia. Since other psychiatric disorders are also more present in relatives of schizophrenia patients, the definition of family history should be broadened. The association between …
The effect of childhood maltreatment and cannabis use on adult psychotic symptoms is modified by the COMT Val¹⁵⁸Met polymorphism
Vinkers CH, Van Gastel WA, Schubart CD, Van Eijk KR, Luykx JJ, Van Winkel R, Joëls M, Ophoff RA, Boks MP, , Bruggeman R, Cahn W, de Haan L, Kahn RS, Meijer CJ, Myin-Germeys I, van Os J, Wiersma D Schizophr. Res. 2013 Oct;150(1):303-11 PMID: 23954148 Abstract BACKGROUND: Cannabis use and childhood maltreatment are independent risk factors for the development …
A two-factor structure of first rank symptoms in patients with a psychotic disorder
Heering HD, van Haren NE, Derks EM, Schizophr. Res. 2013 Jul;147(2-3):269-74 PMID: 23732016 Abstract Kurt Schneider defined ‘first rank symptoms’ (FRS) of psychosis. Previous research found two clusters of FRS: ‘loss of ego bound’ symptoms (e.g., delusions of external control) and auditory hallucinations (e.g, commenting voices). In patients with a psychosis we investigated whether FRS are a separate cluster within …
Substance use in a large sample of patients with schizophrenia or related disorders and co-morbid obsessive-compulsive symptoms
Dekker N, Swets M, Aust N Z J Psychiatry 2013 Sep;47(9):868-74 PMID: 23723291 Abstract OBJECTIVE: The aim of this study was to examine the relationship between obsessive-compulsive symptoms (OCS) and substance use in patients with a non-affective psychotic disorder. METHOD: The data were derived from the Genetic Risk and Outcome of Psychosis study. Using the Yale-Brown Obsessive Compulsive Scale, three …
Cognitive subtypes in non-affected siblings of schizophrenia patients: characteristics and profile congruency with affected family members
Quee PJ, Alizadeh BZ, Aleman A, van den Heuvel ER, Psychol Med 2014 Jan;44(2):395-405 PMID: 23659373 Abstract BACKGROUND: Although cognitive subtypes have been suggested in schizophrenia patients, similar analyses have not been carried out in their non-affected siblings. Subtype classification may provide more insight into genetically driven variation in cognitive function. We investigated cognitive subtypes in siblings. METHOD: Cluster analyses …
Insight change in psychosis: relationship with neurocognition, social cognition, clinical symptoms and phase of illness
Quee PJ, van der Meer L, Krabbendam L, de Haan L, Cahn W, Wiersma D, van Beveren N, Pijnenborg GH, Mulder CL, Bruggeman R, Aleman A Acta Psychiatr Scand 2014 Feb;129(2):126-33 PMID: 23600752 Abstract OBJECTIVE: Impaired insight is an important and prevalent symptom of psychosis. It remains unclear whether cognitive disturbances hamper improvements in insight. We investigated the neurocognitive, social …
Effect of illness expression and liability on familial associations of clinical and subclinical psychosis phenotypes
Lataster T, Verweij K, Viechtbauer W, Acta Psychiatr Scand 2014 Jan;129(1):44-53 PMID: 23465170 Abstract OBJECTIVE: Given the familial influences on schizophrenia, it may be hypothesized that specific symptom domains also cluster within families, and that this applies to both clinical and subclinical levels of expression. This hypothesis was put to the test in a group of patients with a DSM-IV …
Is a schizo-obsessive subtype associated with cognitive impairment? Results from a large cross-sectional study in patients with psychosis and their unaffected relatives
Meijer JH, Swets M, Keeman S, Nieman DH, Meijer CJ, J. Nerv. Ment. Dis. 2013 Jan;201(1):30-5 PMID: 23274292 Abstract The current study investigated whether candidate cognitive endophenotypes may be used to validate a schizo-obsessive subtype. Using within-subject random effect regression analyses and cross-trait cross-relative analyses, we evaluated the association between obsessive-compulsive symptoms (OCSs) and cognitive performance in 984 patients with …