These authors contributed equally to this work.
Effect of illness expression and liability on familial associations of clinical and subclinical psychosis phenotypes
Article first published online: 7 MAR 2013
© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Acta Psychiatrica Scandinavica
Volume 129, Issue 1, pages 44–53, January 2014
How to Cite
GROUP. Effect of illness expression and liability on familial associations of clinical and subclinical psychosis phenotypes., ,
- Issue published online: 12 DEC 2013
- Article first published online: 7 MAR 2013
- Manuscript Accepted: 22 JAN 2013
- Eli Lilly
- Envivo. Grant Number: 10-000-1002
- Dutch Health Research Council
- European Community. Grant Number: 10-000-1002
- Eli Lilly
- Pfizer. Grant Numbers: 10-000-1002, HEALTH-F2-2009-241909
- family studies;
- genetic epidemiology;
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 diagnosis of psychotic disorder together with their unaffected siblings, and a group of healthy sib-pairs.
Subclinical positive, negative and depressive symptoms in relatives and healthy controls were assessed with the Community Assessment of Psychic Experiences (CAPE). Positive and negative schizotypy in relatives and controls was measured with the Structured Interview for Schizotypy–Revised. Multilevel linear regression analyses were conducted to investigate clustering of symptom dimensions within patient–relative sib-pairs (N = 811 pairs), healthy sib-pairs of affected families (N = 136 pairs) and healthy control sib-pairs (N = 58 pairs).
Familial clustering of symptoms was found in all three groups. Effect sizes were largest in healthy control sib-pairs, smallest in patient–relative sib-pairs and intermediate in healthy sib-pairs of affected families.
Studies of sibling associations in genetic studies of psychometric expression of psychosis liability need to take into account the fact that the higher levels of background genetic risk and presence of diagnosed illness are inversely associated with sibling associations.