Examining the independent and joint effects of genomic and exposomic liabilities for schizophrenia across the psychosis spectrum
L.-K. Pries, Giovanni Ferro, Jim van Os, Philippe Delespaul, Günter Kenis, Bochao Lin, Jurjen J. Luykx, Alexander Richards, Berna Binnur Akdede, Tolga Binbay, Vesile Altınyazar, Berna Yalınçetin, Güvem Gümüş‐Akay, Burçin Cihan, Haldun Soygür, Halis Ulaş, Eylem Şahin Cankurtaran, Semra Ulusoy Kaymak, Marina Mihaljević, Sanja Andrić Petrović, Tijana Mirjanić, Miquel Bernardo, Gisela Mezquida, Sílvia Amoretti, Julio Bobes, Pilar A. Sáiz, María Paz García‐Portilla, Julio Sanjuán, Eduardo J. Aguilar, José Luis Santos, Estela Jiménez‐López, Manuel Arrojo, Ãngel Carracedo, Gonzalo López, Javier González‐Peñas, Mara Parellada, Nadja P. Marić, Cem Atbaşoğlu, A. Ucok, Köksal Alptekın, Meram Can Saka, Genetic Risk and Outcome of Psychosis (GROUP) investigators, Celso Arango, Michael O‘Donovan, Sarah Tosato, Bart P. F. Rutten, Sinan Gülöksüz
Abstract
AIMS: Psychosis spectrum disorder has a complex pathoetiology characterised by interacting environmental and genetic vulnerabilities. The present study aims to investigate the role of gene-environment interaction using aggregate scores of genetic (polygenic risk score for schizophrenia (PRS-SCZ)) and environment liability for schizophrenia (exposome score for schizophrenia (ES-SCZ)) across the psychosis continuum. METHODS: The sample consisted of 1699 patients, 1753 unaffected siblings, and 1542 healthy comparison participants. The Structured Interview for Schizotypy-Revised (SIS-R) was administered to analyse scores of total, positive, and negative schizotypy in siblings and healthy comparison participants. The PRS-SCZ was trained using the Psychiatric Genomics Consortiums results and the ES-SCZ was calculated guided by the approach validated in a previous report in the current data set. Regression models were applied to test the independent and joint effects of PRS-SCZ and ES-SCZ (adjusted for age, sex, and ancestry using 10 principal components). RESULTS: Both genetic and environmental vulnerability were associated with case-control status. Furthermore, there was evidence for additive interaction between binary modes of PRS-SCZ and ES-SCZ (above 75% of the control distribution) increasing the odds for schizophrenia spectrum diagnosis (relative excess risk due to interaction = 6.79, [95% confidential interval (CI) 3.32, 10.26], p < 0.001). Sensitivity analyses using continuous PRS-SCZ and ES-SCZ confirmed gene-environment interaction (relative excess risk due to interaction = 1.80 [95% CI 1.01, 3.32], p = 0.004). In siblings and healthy comparison participants, PRS-SCZ and ES-SCZ were associated with all SIS-R dimensions and evidence was found for an interaction between PRS-SCZ and ES-SCZ on the total (B = 0.006 [95% CI 0.003, 0.009], p < 0.001), positive (B = 0.006 [95% CI, 0.002, 0.009], p = 0.002), and negative (B = 0.006, [95% CI 0.004, 0.009], p < 0.001) schizotypy dimensions. CONCLUSIONS: The interplay between exposome load and schizophrenia genetic liability contributing to psychosis across the spectrum of expression provide further empirical support to the notion of aetiological continuity underlying an extended psychosis phenotype.