Finally, a significant source of heterogeneity in depression is comorbidity with other forms of psychopathology. Given the high rates of comorbidity, particularly with the anxiety disorders, associations between personality and depressive disorders may actually reflect the relation of personality with a co-occurring nonmood disorder. Indeed, personality may be a third variable that explains broad patterns of comorbidity among many disorders. For example, recent hierarchical models of classification posit that trait dispositions such as N/NE account for much of the comorbidity between depression and other disorders (Griffith et al. 2010, Kotov et al. 2007). Thus, it is important for researchers to consider whether traits have specific relations with depression over and above more general associations with the broader group of internalizing disorders.
