M Aas1, I Melle1, F Bettella1, S Djurovic1, S Le Hellard2, T Bjella1, P A Ringen1, T V Lagerberg1, O B Smeland1, I Agartz3, O A Andreassen1, M Tesli1. 1. NORMENT,KG Jebsen Centre for Psychosis Research,Institute of Clinical Medicine,University of Oslo,and Division of Mental Health and Addiction,Oslo University Hospital,Oslo,Norway. 2. NORMENT,KG Jebsen Centre for Psychosis Research,Department of Clinical Science,University of Bergen,Bergen,Norway. 3. NORMENT,KG Jebsen Centre for Psychosis Research,Division of Mental Health and Addiction,University of Oslo,Oslo,Norway.
Abstract
BACKGROUND: Schizophrenia (SZ) and bipolar disorder (BD) are heritable, polygenic disorders with shared clinical and genetic components, suggesting a psychosis continuum. Cannabis use is a well-documented environmental risk factor in psychotic disorders. In the current study, we investigated the relationship between SZ genetic load and cannabis use before illness onset in SZ and BD spectrums. Since frequent early cannabis use (age <18 years) is believed to increase the risk of developing psychosis more than later use, follow-up analyses were conducted comparing early use to later use and no use. METHODS: We assigned a SZ-polygenic risk score (PGRS) to each individual in our independent sample (N = 381 SZ spectrum cases, 220 BD spectrum cases and 415 healthy controls), calculated from the results of the Psychiatric Genomics Consortium (PGC) SZ case-control study (N = 81 535). SZ-PGRS in patients who used cannabis weekly to daily in the period before first illness episode was compared with that of those who never or infrequently used cannabis. RESULTS: Patients with weekly to daily cannabis use before illness onset had the highest SZ-PGRS (p = 0.02, Cohen's d = 0.33). The largest difference was found between patients with daily or weekly cannabis use before illness onset <18 years of age and patients with no or infrequent use of cannabis (p = 0.003, Cohen's d = 0.42). CONCLUSIONS: Our study supports an association between high SZ-PGRS and frequent cannabis use before illness onset in psychosis continuum disorders.
BACKGROUND:Schizophrenia (SZ) and bipolar disorder (BD) are heritable, polygenic disorders with shared clinical and genetic components, suggesting a psychosis continuum. Cannabis use is a well-documented environmental risk factor in psychotic disorders. In the current study, we investigated the relationship between SZ genetic load and cannabis use before illness onset in SZ and BD spectrums. Since frequent early cannabis use (age <18 years) is believed to increase the risk of developing psychosis more than later use, follow-up analyses were conducted comparing early use to later use and no use. METHODS: We assigned a SZ-polygenic risk score (PGRS) to each individual in our independent sample (N = 381 SZ spectrum cases, 220 BD spectrum cases and 415 healthy controls), calculated from the results of the Psychiatric Genomics Consortium (PGC) SZ case-control study (N = 81 535). SZ-PGRS in patients who used cannabis weekly to daily in the period before first illness episode was compared with that of those who never or infrequently used cannabis. RESULTS:Patients with weekly to daily cannabis use before illness onset had the highest SZ-PGRS (p = 0.02, Cohen's d = 0.33). The largest difference was found between patients with daily or weekly cannabis use before illness onset <18 years of age and patients with no or infrequent use of cannabis (p = 0.003, Cohen's d = 0.42). CONCLUSIONS: Our study supports an association between high SZ-PGRS and frequent cannabis use before illness onset in psychosis continuum disorders.
Authors: Alice Caldiroli; Enrico Capuzzi; Jennifer L Barkin; Silvia Grassi; Cecilia Maria Esposito; Anna Maria Auxilia; Stefania Russo; Ilaria Tagliabue; Greta Silvia Carnevali; Francesco Mucci; Elena Invernizzi; Massimo Clerici; Massimiliano Buoli Journal: Brain Behav Immun Health Date: 2022-03-19