Residual symptoms and recurrence during maintenance treatment of late-life depression

Background: Many older patients who recover from an episode of major depression continue to suffer from depressed mood, anxiety, and sleep problems. Our study assesses the impact of these residual symptoms on the risk of recurrence during maintenance treatment of late-life depression. Method: We analyzed data from a randomized clinical trial of maintenance treatment in patients with unipolar depression aged ≥ 70, 116 of whom remitted and remained stable during open pharmacotherapy and interpersonal psychotherapy (IPT) and were randomized to clinical management/pharmacotherapy; clinical management/placebo; monthly maintenance IPT/ pharmacotherapy; or monthly maintenance IPT/placebo. We assessed the impact of overall residual symptoms (based on the Hamilton Depression Rating Scale (HAM-D) total score) and of specific residual symptom clusters - mood symptoms (depressed mood, guilt, suicidality, energy/interests), sleep disturbance (early, middle, late insomnia), and anxiety (agitation, psychic and somatic anxiety, hypochondriasis) measured at randomization. Sleep disturbance was also assessed with the Pittsburgh Sleep Quality Index (PSQI). We used Cox proportional hazards regression models controlling for assignment to antidepressant medication versus placebo to identify predictors of recurrence. Results: Residual anxiety and residual sleep disturbance (as measured by the PSQI but not the HAM-D) independently predicted early recurrence. Limitations: Use of HAM-D clusters to define residual symptoms; analysis limited to completers of acute and continuation treatment. Conclusions: In patients with late-life depression who have remitted with pharmacotherapy and psychotherapy, the deleterious effect of residual symptoms is due to persisting anxiety and, possibly, residual sleep disturbance.