In the current study, we examine whether the comorbidity between symptoms of major depressive episode, generalized anxiety, panic attack, and ratings of neuroticism can be explained by a continuous underlying spectrum that is genetically influenced. Further, we were interested in whether this common internalizing spectrum could account for all genetic influences shared between the syndromes, or whether there would be genetic effects specific to each disorder. We then estimated the degree of genetic and environmental overlap between the internalizing spectrum and marital quality. Finally, we examined whether marital quality moderates the genetic and environmental influences on the internalizing spectrum. Evidence of significant moderation would suggest that the marital relationship may act as an environmental stressor that allows for the expression of a genetic predisposition to internalizing spectrum syndromes.
