Castle, D. & Bosanac, P. Depression and schizophrenia. Adv. Psychiatr. Treat. 18, 280–288 (2012).
Samsom, J. N. & Wong, A. H. Schizophrenia and depression co-morbidity: what we have learned from animal models. Front. Psychiatry 6, 13 (2015).
Li, W. et al. Prevalence of comorbid depression in schizophrenia: a meta-analysis of observational studies. J. Affect. Disord. 273, 524–531 (2020).
Conley, R. R., Ascher-Svanum, H., Zhu, B., Faries, D. E. & Kinon, B. J. The burden of depressive symptoms in the long-term treatment of patients with schizophrenia. Schizophr. Res. 90, 186–197 (2007).
Dutta, R., Murray, R. M., Allardyce, J., Jones, P. B. & Boydell, J. Early risk factors for suicide in an epidemiological first episode psychosis cohort. Schizophr. Res. 126, 11–19 (2011).
Dubovsky, S. L., Ghosh, B. M., Serotte, J. C. & Cranwell, V. Psychotic depression: diagnosis, differential diagnosis, and treatment. Psychother. Psychosom. 90, 160–177 (2021).
Goldberg, E. M. & Morrison, S. L. Schizophrenia and social class. Br. J. Psychiatry 109, 785–802 (1963).
Dai, J., Xu, Y., Wang, T. & Zeng, P. Exploring the relationship between socioeconomic deprivation index and Alzheimer’s disease using summary-level data: from genetic correlation to causality. Prog. Neuropsychopharmacol. Biol. Psychiatry 123, 110700 (2023).
Matthews, K. A. & Gallo, L. C. Psychological perspectives on pathways linking socioeconomic status and physical health. Annu. Rev. Psychol. 62, 501–530 (2011).
Kivimäki, M. et al. Association between socioeconomic status and the development of mental and physical health conditions in adulthood: a multi-cohort study. Lancet Public Health 5, e140–e149 (2020).
Burns, J. K., Tomita, A. & Kapadia, A. S. Income inequality and schizophrenia: increased schizophrenia incidence in countries with high levels of income inequality. Int. J. Soc. Psychiatry 60, 185–196 (2014).
Werner, S., Malaspina, D. & Rabinowitz, J. Socioeconomic status at birth is associated with risk of schizophrenia: population-based multilevel study. Schizophr. Bull. 33, 1373–1378 (2007).
Agerbo, E. et al. Polygenic risk score, parental socioeconomic status, family history of psychiatric disorders, and the risk for schizophrenia: a Danish Population-Based Study and Meta-analysis. JAMA Psychiatry 72, 635–641 (2015).
Weich, S. & Lewis, G. Poverty, unemployment, and common mental disorders: population based cohort study. BMJ 317, 115–119 (1998).
Saraceno, B., Levav, I. & Kohn, R. The public mental health significance of research on socio-economic factors in schizophrenia and major depression. World Psychiatry 4, 181–185 (2005).
Marees, A. T. et al. Genetic correlates of socio-economic status influence the pattern of shared heritability across mental health traits. Nat. Hum. Behav. 5, 1065–1073 (2021).
Upthegrove, R., Marwaha, S. & Birchwood, M. Depression and schizophrenia: cause, consequence, or trans-diagnostic issue? Schizophr. Bull. 43, 240–244 (2017).
Trubetskoy, V. et al. Mapping genomic loci implicates genes and synaptic biology in schizophrenia. Nature 604, 502–508 (2022).
Jones, D. S. & Podolsky, S. H. The history and fate of the gold standard. Lancet 385, 1502–1503 (2015).
Lin, L. J., Wei, Y. Y., Zhang, R. Y. & Chen, F. Application of Mendelian randomization methods in causal inference of observational study. Chin. J. Prev. Med. 53, 619–624 (2019).
Smith, G. D. & Ebrahim, S. ‘Mendelian randomization’: can genetic epidemiology contribute to understanding environmental determinants of disease? Int. J. Epidemiol. 32, 1–22 (2003).
Emdin, C. A., Khera, A. V. & Kathiresan, S. Mendelian randomization. JAMA 318, 1925–1926 (2017).
Burgess, S. et al. Guidelines for performing Mendelian randomization investigations. Wellcome Open Res. 4, 186 (2019).
Lawlor, D. A., Harbord, R. M., Sterne, J. A., Timpson, N. & Davey Smith, G. Mendelian randomization: using genes as instruments for making causal inferences in epidemiology. Stat. Med. 27, 1133–1163 (2008).
Zheng, J. et al. Recent developments in Mendelian randomization studies. Curr. Epidemiol. Rep. 4, 330–345 (2017).
Saccaro, L. F., Gasparini, S. & Rutigliano, G. Applications of Mendelian randomization in psychiatry: a comprehensive systematic review. Psychiatr. Genet. 32, 199–213 (2022).
Zhu, D. et al. Total brain volumetric measures and schizophrenia risk: a two-sample Mendelian Randomization Study. Front. Genet. 13, 782476 (2022).
Didelez, V. & Sheehan, N. Mendelian randomization as an instrumental variable approach to causal inference. Stat. Methods Med. Res. 16, 309–330 (2007).
Davies, N. M., Holmes, M. V. & Davey Smith, G. Reading Mendelian randomisation studies: a guide, glossary, and checklist for clinicians. BMJ 362, k601 (2018).
Wray, N. R. et al. Genome-wide association analyses identify 44 risk variants and refine the genetic architecture of major depression. Nat. Genet. 50, 668–681 (2018).
Lee, J. J. et al. Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals. Nat. Genet. 50, 1112–1121 (2018).
Burgess, S., Davies, N. M. & Thompson, S. G. Bias due to participant overlap in two-sample Mendelian randomization. Genet. Epidemiol. 40, 597–608 (2016).
Dudbridge, F. & Gusnanto, A. Estimation of significance thresholds for genomewide association scans. Genet. Epidemiol. 32, 227–234 (2008).
Uffelmann, E. et al. Genome-wide association studies. Nat. Rev. Methods Primers 1, 59 (2021).
Purcell, S. et al. PLINK: a tool set for whole-genome association and population-based linkage analyses. Am. J. Hum. Genet. 81, 559–575 (2007).
Machiela, M. J. & Chanock, S. J. LDlink: a web-based application for exploring population-specific haplotype structure and linking correlated alleles of possible functional variants. Bioinformatics 31, 3555–3557 (2015).
Hemani, G., Tilling, K. & Davey Smith, G. Orienting the causal relationship between imprecisely measured traits using GWAS summary data. PLoS Genet. 13, e1007081 (2017).
Gormley, M. et al. A multivariable Mendelian randomization analysis investigating smoking and alcohol consumption in oral and oropharyngeal cancer. Nat. Commun. 11, 6071 (2020).
Wootton, R. E. et al. Evaluation of the causal effects between subjective wellbeing and cardiometabolic health: Mendelian randomisation study. BMJ 362, k3788 (2018).
Burgess, S. & Thompson, S. G. Avoiding bias from weak instruments in Mendelian randomization studies. Int. J. Epidemiol. 40, 755–764 (2011).
Pierce, B. L., Ahsan, H. & Vanderweele, T. J. Power and instrument strength requirements for Mendelian randomization studies using multiple genetic variants. Int. J. Epidemiol. 40, 740–752 (2011).
Burgess, S. Sample size and power calculations in Mendelian randomization with a single instrumental variable and a binary outcome. Int. J. Epidemiol. 43, 922–929 (2014).
Bowden, J. et al. A framework for the investigation of pleiotropy in two-sample summary data Mendelian randomization. Stat. Med. 36, 1783–1802 (2017).
Hemani, G., Bowden, J. & Davey Smith, G. Evaluating the potential role of pleiotropy in Mendelian randomization studies. Hum. Mol. Genet. 27, R195–R208 (2018).
Bowden, J., Davey Smith, G. & Burgess, S. Mendelian randomization with invalid instruments: effect estimation and bias detection through Egger regression. Int. J. Epidemiol. 44, 512–525 (2015).
Bowden, J. et al. Assessing the suitability of summary data for two-sample Mendelian randomization analyses using MR-Egger regression: the role of the I2 statistic. Int. J. Epidemiol. 45, 1961–1974 (2016).
Bowden, J., Davey Smith, G., Haycock, P. C. & Burgess, S. Consistent estimation in Mendelian randomization with some invalid instruments using a weighted median estimator. Genet. Epidemiol. 40, 304–314 (2016).
Sanderson, E., Davey Smith, G., Windmeijer, F. & Bowden, J. An examination of multivariable Mendelian randomization in the single-sample and two-sample summary data settings. Int. J. Epidemiol. 48, 713–727 (2019).
Burgess, S. & Thompson, S. G. Multivariable Mendelian randomization: the use of pleiotropic genetic variants to estimate causal effects. Am. J. Epidemiol. 181, 251–260 (2015).
Rees, J. M. B., Wood, A. M. & Burgess, S. Extending the MR-Egger method for multivariable Mendelian randomization to correct for both measured and unmeasured pleiotropy. Stat. Med. 36, 4705–4718 (2017).
VanderWeele, T. J. Mediation analysis: a practitioner’s guide. Annu. Rev. Public Health 37, 17–32 (2016).
Carter, A. R. et al. Understanding the consequences of education inequality on cardiovascular disease: Mendelian randomisation study. BMJ 365, l1855 (2019).
Cheung, M. W. Comparison of methods for constructing confidence intervals of standardized indirect effects. Behav. Res. Methods 41, 425–438 (2009).
Verbanck, M., Chen, C. Y., Neale, B. & Do, R. Detection of widespread horizontal pleiotropy in causal relationships inferred from Mendelian randomization between complex traits and diseases. Nat. Genet. 50, 693–698 (2018).
Hemani, G. et al. The MR-Base platform supports systematic causal inference across the human phenome. Elife 7, e34408 (2018).
Buckley, P. F., Miller, B. J., Lehrer, D. S. & Castle, D. J. Psychiatric comorbidities and schizophrenia. Schizophr. Bull. 35, 383–402 (2009).
Ohayon, M. M. & Schatzberg, A. F. Prevalence of depressive episodes with psychotic features in the general population. Am. J. Psychiatry 159, 1855–1861 (2002).
Cross-Disorder Group of the Psychiatric Genomics, C., Lee, S. H. et al. Genetic relationship between five psychiatric disorders estimated from genome-wide SNPs. Nat. Genet. 45, 984–994 (2013).
Sonmez, N., Romm, K. L., Andreasssen, O. A., Melle, I. & Rossberg, J. I. Depressive symptoms in first episode psychosis: a one-year follow-up study. BMC Psychiatry 13, 106 (2013).
McGlashan, T. H. & Carpenter, W. T. Jr Postpsychotic depression in schizophrenia. Arch. Gen. Psychiatry 33, 231–239 (1976).
Park, S. C. et al. Distinctive clinical correlates of psychotic major depression: the CRESCEND Study. Psychiatry Investig. 11, 281–289 (2014).
Gournellis, R., Oulis, P. & Howard, R. Psychotic major depression in older people: a systematic review. Int. J. Geriatr. Psychiatry 29, 789–796 (2014).
Krynicki, C. R., Upthegrove, R., Deakin, J. F. W. & Barnes, T. R. E. The relationship between negative symptoms and depression in schizophrenia: a systematic review. Acta Psychiatr. Scand. 137, 380–390 (2018).
Birchwood, M., Iqbal, Z. & Upthegrove, R. Psychological pathways to depression in schizophrenia: studies in acute psychosis, post psychotic depression and auditory hallucinations. Eur. Arch. Psychiatry Clin. Neurosci. 255, 202–212 (2005).
Byrne, M., Agerbo, E., Eaton, W. W. & Mortensen, P. B. Parental socio-economic status and risk of first admission with schizophrenia—a Danish national register based study. Soc. Psychiatry Psychiatr. Epidemiol. 39, 87–96 (2004).
Tesli, M. et al. Educational attainment and mortality in schizophrenia. Acta Psychiatr. Scand. 145, 481–493 (2022).
Sariaslan, A. et al. Schizophrenia and subsequent neighborhood deprivation: revisiting the social drift hypothesis using population, twin and molecular genetic data. Transl. Psychiatry 6, e796 (2016).
Freeman, A. et al. The role of socio-economic status in depression: results from the COURAGE (aging survey in Europe). BMC Public Health 16, 1098 (2016).
Hoebel, J., Maske, U. E., Zeeb, H. & Lampert, T. Social inequalities and depressive symptoms in adults: the role of objective and subjective socioeconomic status. PLoS ONE 12, e0169764 (2017).
Ye, J. et al. Socioeconomic deprivation index is associated with psychiatric disorders: an observational and genome-wide gene-by-environment interaction analysis in the UK Biobank Cohort. Biol. Psychiatry 89, 888–895 (2021).
Cai, J. et al. Socioeconomic status, individual behaviors and risk for mental disorders: a Mendelian randomization study. Eur. Psychiatry 65, e28 (2022).
Campbell, D. et al. Effects of depression on employment and social outcomes: a Mendelian randomisation study. J. Epidemiol. Community Health 76, 563–571 (2022).