Improved cognitive content endures for 2 years among unstable responders to acute-phase cognitive therapy for recurrent major depressive disorder.

Abstract

The cognitive model of depression suggests that cognitive therapy (CT) improves major depressive disorder (MDD) in part by changing depressive cognitive content (e.g. dysfunctional attitudes, hopelessness). The current analyses clarified: (1) the durability of improvements in cognitive content made by acute-phase CT responders; (2) whether continuation-phase CT (C-CT) or fluoxetine (FLX) further improves cognitive content; and (3) the extent to which cognitive content mediates continuation treatments' effects on depressive symptoms and major depressive relapse/recurrence. Out-patients with recurrent MDD who responded to acute-phase CT (n = 241) were randomized to 8 months of C-CT, FLX or pill placebo (PBO) and followed for an 24 additional months. Cognitive content was assessed approximately every 4 months using five standard patient-report measures. Large improvements in cognitive content made during acute-phase CT were maintained for 32 months, with 78-90% of patients scoring in normal ranges, on average. Cognitive content varied little between C-CT, FLX and PBO arms, overall. Small, transient improvements in cognitive content in C-CT or FLX compared with PBO patients did not clearly mediate the treatments' effects on depressive symptoms or on major depressive relapse/recurrence. Outpatients with recurrent MDD who respond to acute-phase CT show durable improvements in cognitive content. C-CT or FLX may not continue to improve patient-reported cognitive content substantively, and thus may treat recurrent MDD by other paths.