Genetic and Environmental Contribution to Major Depressive Disorder and Self-declared Depression

Abstract

Major depressive disorder (MDD) is a high-prevalence disease (~ 15%) that is the fifth leading disease contributing to disability-adjusted life years (DALYs) in the US (Murray et al., 2013). The pathogenesis of MDD is still partially unknown, consequently diagnosis is based on clinical criteria. However, MDD is a clinically heterogeneous disorder and this probably reflects heterogeneity in the underlying biology. Since ~ 20 years, genetic variants are known to be involved in MDD biology thanks to family studies (Sullivan et al., 2000) and recently genome-wide association studies (GWAS) (Hyde et al., 2016). The estimation of genetic variants contribution and the identification of specific variants involved have been difficult partly because of the heterogeneity and high prevalence of MDD (Gratten et al., 2014). The consequent large sample sizes required to provide adequate statistical power are difficult to recruit and self-declared depression (SDD) is an interesting option to face this issue.