In light of the central role of cognitive theories in depression, there has been surprisingly little research on cognitive factors in chronic depression. Patients with DD and double depression report higher levels of self-criticism than those with nonchronic MDD.44 In addition, Riso et al.50 found that patients with chronic depression exhibited significantly higher levels of dysfunctional attitudes and maladaptive cognitive schemas and core beliefs than patients with nonchronic depression and that these differences persisted after controlling for concurrent depressive symptoms.
Few prospective studies have been conducted to determine whether cognitive variables precede the development of chronicity or are a consequence of persistent depression, whether cognitive variables and depression have reciprocal effects on one another, or whether both depressive cognitions and symptoms are caused by a third variable. In one of the few studies addressing this issue, Arnow et al.51 modeled the associations among rumination, distraction, and depressive symptomatology over the course of 12 weeks in a large sample of patients with double depression and chronic major depression. A model positing that depression and rumination are both caused by the same factors provided a better fit to the data than models positing that rumination causes subsequent depression or that depression causes subsequent rumination.