Exploring the comorbidity between internalizing/externalizing dimensions and cognitive disengagement syndrome through twin studies: a narrative review

Twin studies are cutting-edge design methodologies proper to behavioral genetics that aim to investigate how the interplay between genetic and environmental factors can concur to explain individual differences in psychopathology, temperamental traits, and behavior. This particular research design has been widely applied to the study of comorbidity between internalizing (INT) and externalizing (EXT) symptoms, especially in childhood and adolescence. Notably, the high co-occurrence of symptoms of both these diagnostic domains has led to the hypothesis that at their basis, there might be one single latent common susceptibility factor, namely p factor. Twin studies have contributed to marking a relevant turning point in this regard by highlighting the consistent genetic nature of this factor. In light of these premises, the present narrative review aims to outline the path for future twin studies in investigating the comorbidity between Cognitive Disengagement Syndrome (CDS) and INT-EXT disorders, examining the evidence supporting this need and its clinical implications. Since CDS has not been recognized as a stand-alone syndrome until very recently, research on this condition is still in its infancy and the etiological factors at the basis of its comorbidity with INT-EXT are still unclear. Being aware of the causal factors underneath the comorbidity between INT-EXT might pave the way for improving assessment diagnostic procedures as well as setting up preventive interventions for CDS.