Which symptoms predict recurrence of depression in women treated with maintenance interpersonal psychotherapy?

BACKGROUND Even low levels of residual symptoms are known to increase the risk of relapse and early recurrence of major depression. It is not known if ongoing psychotherapy lessens this risk. We therefore examined the impact of persistent symptoms, including mood, insomnia, and anxiety symptoms, on time to recurrence in women receiving maintenance interpersonal psychotherapy (IPT-M) for recurrent depression. METHODS We analyzed data on 131 women aged 20-60 from a 2-year randomized trial of weekly versus twice-monthly versus monthly IPT-M. Participants achieved remission with IPT alone (n=99) or IPT plus sequential antidepressant medication (n=32). Medications were tapered before starting maintenance treatment. Residual symptoms were assessed with the Hamilton Rating Scale for Depression (HRSD; total score and subscales); insomnia was also assessed in 76 women with the Pittsburgh Sleep Quality Index (PSQI). Data analyses used Cox proportional hazards regression models. RESULTS Neither overall burden of residual symptoms (HRSD total score), nor HRSD mood and anxiety subscale scores predicted recurrence during ongoing IPT-M. In contrast, persistent insomnia measured both by the HRSD-17 insomnia subscale and the PSQI predicted recurrence. Women with persistent insomnia who required sequential pharamacotherapy had the highest recurrence rate (65%) compared to women requiring sequential treatment without insomnia (13%), or women who had recovered with IPT alone but had persistent insomnia (21%) or no insomnia (18%). CONCLUSIONS Persistent insomnia following the recovery from an episode of recurrent major depression is associated with increased risk of recurrence despite maintenance psychotherapy, particularly for those withdrawn from antidepressant medication.