Shared genetic influences between depression and conduct disorder in children and adolescents: A systematic review

The co-occurrence between major depression disorder (MDD) and conduct disorder (CD) is common across development and represents a significant risk factor for future psychiatric problems and long-term impairment. Large-scale quantitative genetic studies suggest that the MDD-CD co-occurrence may be partly explained by shared genetic vulnerability factors, in line with transdiagnostic models of psychopathology, but no systematic synthesis of the literature is currently available. We therefore conducted a systematic review of the available genetic literature on the co-occurrence between MDD and CD in children and adolescents. We identified 10 eligible studies, including 5 cross-sectional bivariate/multivariate twin studies, 3 longitudinal bivariate/multivariate twin studies, and 2 latent profile/trajectory twin studies. Most of the reviewed studies found a strong contribution of shared genetic factors on the covariation between depression and conduct problems, in line with the prominent effect of a common genetic liability across development. The scientific literature on this psychiatric comorbidity is still limited, as it solely consists of twin studies from high income countries. Considering the joint burden of MDD and CD on youth, families and society worldwide, future studies are needed to better investigate the shared risk processes of these frequently co-occurring conditions, in order to support new treatment trough personalized medicine. • Common genetic liability explains MDD-CD co-occurrence over development. • Results confirm transdiagnostic and hierarchical causal models of psychopathology. • MDD-CD co-occurrence needs further study using multiple genetic approaches. • Transdiagnostic strategies to detect co-occurring conditions are required.