Levels of depressed mood and low interest for two years after response to cognitive therapy for recurrent depression

Background: Major depressive disorder (MDD) involves depressed mood (high negative affect, predominantly) and low interest/pleasure (low positive affect). In past research, negative affect has improved more than positive affect during acute-phase antidepressant medication or cognitive therapy (CT). We extended this literature by differentiating depressed mood and two dimensions of low interest (general and sexual), assessing persistence of symptom differences after acute-phase CT response, and testing whether continuation treatment acted differently on depressed mood versus low interest. Methods: We analyzed data from two randomized controlled trials. Patients with recurrent MDD first received acute-phase CT. Then, responders were randomized to 8-month continuation treatments and assessed for 16-24 additional months. Results: Depressed mood and low general interest improved more than low sexual interest during acute-phase CT. Among responders, these symptom differences persisted for at least 2 years and were not changed by continuation CT or antidepressant medication. Limitations: Generalization of findings to other patient populations and treatments is uncertain. Depressed mood and low interest scales were constructed from standard symptom measures and overlapped empirically. Conclusions: Less improvement during CT, and persistent low sexual interest despite continuation treatment, highlights the need for MDD treatments more effectively targeting this positive affective symptom.