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Genetic and environmental contribution to psychosis-risk symptoms and social functioning in clinical high-risk youth: A discordant sibling-pair analysis
Social functioning shows positive phenotypic associations with symptoms of psychosis-risk syndrome (Scale of Psychosis-risk Symptoms, SOPS) in clinical high risk (CHR) youth and in discordant (non-CHR) siblings. Cross-sibling, cross-trait analyses of social functioning and psychosis-risk symptoms supported both positive and negative phenotypic associations, as well as no association. This suggests important familial differences. However, genetic and environmental contribution to these associations has not been examined. This information is key to understanding early differences in psychosis vulnerability and guiding subsequent research in this area. Method: CHR probands (n=18) and their discordant (non-CHR) full biological siblings (n=26) were assessed on psychosis-risk symptoms [Structured Interview for Psychosis-risk Syndromes (SIPS)/SOPS], premorbid social adjustment (Premorbid Adjustment Scale), and baseline social functioning [Global Functioning: Social scale (GF:S)]. Polygenic analyses were conducted using SOLAR (Sequential Oligogenic Linkage Analysis Routines). Results: Heritability and genetic association analyses indicated contribution of genetic factors was generally small, whereas analyses of environmental effects indicated significant contribution of unshared environmental factors. Conclusion: Associations between social functioning and psychosis-risk symptoms appear more strongly influenced by environmental experience than genetic factors. In progress secondary analyses examine these effects in greater detail. Guided by these results, the next step will be to identify those unshared environmental experiences that best discriminate between high- and low-risk relatives.