Introduction: 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.
Methods: 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.
Results: 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.
Limitations: The scientific literature on this psychiatric comorbidity is still limited, as it solely consists of twin studies from high income countries.
Conclusion: 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 inform new treatments through personalized medicine.
Keywords: Co-occurrence; Conduct disorder; Depression; Development; Genetic factors.
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