Subclinical psychotic experiences and cognitive functioning as a bivariate phenotype for genetic studies in the general population

Simons, C.J.P.; Jacobs, N.; Jolles, J.; van Os, J.; Krabbendam, L.

doi:10.1016/j.schres.2007.01.008

« Previous Next »Schizophrenia Research
Volume 92, Issue 1 , Pages 24-31, May 2007

Subclinical psychotic experiences and cognitive functioning as a bivariate phenotype for genetic studies in the general population

C.J.P. Simons
- Department of Psychiatry and Neuropsychology, Maastricht University, European Graduate School of Neuroscience, SEARCH, P.O. Box 616, 6200 MD Maastricht, The Netherlands
N. Jacobs
- Department of Psychiatry and Neuropsychology, Maastricht University, European Graduate School of Neuroscience, SEARCH, P.O. Box 616, 6200 MD Maastricht, The Netherlands
- Faculty of Psychology, Open University of the Netherlands, P.O. Box 2960, 6401 DL Heerlen, The Netherlands
J. Jolles
- Department of Psychiatry and Neuropsychology, Maastricht University, European Graduate School of Neuroscience, SEARCH, P.O. Box 616, 6200 MD Maastricht, The Netherlands
J. van Os
- Department of Psychiatry and Neuropsychology, Maastricht University, European Graduate School of Neuroscience, SEARCH, P.O. Box 616, 6200 MD Maastricht, The Netherlands
- Division of Psychological Medicine, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, United Kingdom
L. Krabbendam
- Department of Psychiatry and Neuropsychology, Maastricht University, European Graduate School of Neuroscience, SEARCH, P.O. Box 616, 6200 MD Maastricht, The Netherlands
- Corresponding author. Department of Psychiatry and Neuropsychology, Maastricht University, P.O. Box 616 (VIJV1), 6200 MD Maastricht, The Netherlands. Tel.: +31 43 3688682; fax: +31 43 3688689.

Received 4 July 2006; received in revised form 9 November 2006; accepted 14 January 2007. published online 12 March 2007.

Abstract

Objective

Cognitive deficits may be vulnerability markers for the development of schizophrenia. This study examined whether cognitive deficits are related to specific dimensions of subclinical psychotic experiences and whether associations between these variables are caused by additive genetic, common environmental and/or individual-specific environmental factors.

Method

A general population sample of 298 female twin pairs completed the Community Assessment of Psychic Experiences and a neuropsychological test battery. Associations between subclinical positive and negative psychotic dimensions and neuropsychological factors (episodic memory and information processing speed) were examined. Univariate correlation and structural equation analyses were performed to explore the role of genetic and environmental factors in the phenotypes separately. Bivariate correlation and structural equation analyses were applied to examine the causes of association.

Results

There were significant correlations between information processing speed and both the positive (r=.11; p<.05) and the negative dimension (r=.10; p<.05). For the negative dimension and for speed of processing, the data suggested a model that included genetic factors. The observed phenotypic correlation between the negative dimension and information processing speed could be solely explained in terms of additive genetic factors. Although the comparison of the correlations for MZ and DZ pairs did not give a clear indication as to the underlying causes of the association, structural equation modelling suggested that the observed phenotypic correlation between the negative dimension and information processing speed could be solely explained in terms of additive genetic factors.

Conclusion

Negative symptoms and information processing speed are associated at the subclinical level and this association appears to be influenced by genetic factors exclusively. Bivariate psychosis phenotypes may represent suitable candidates for molecular genetic studies in the general population.

Keywords: Psychosis, Psychosis-proneness, Schizotypy, Cognition, Twins, Genetic analysis