Treating insomnia in depression: Insomnia related factors predict long-term depression trajectories

Abstract

Objective: Insomnia and major depressive disorders (MDD) often co-occur, and such comorbidity has been associated with poorer outcomes for both conditions. However, individual differences in depressive symptom trajectories during and after treatment are poorly understood in comorbid insomnia and depression. This study explored the heterogeneity in long-term depression change trajectories, and examined their correlates, particularly insomnia-related characteristics.

Method: Participants were 148 adults (age M ± SD = 46.6 ± 12.6, 73.0% female) with insomnia and MDD who received antidepressant pharmacotherapy, and were randomized to 7-session Cognitive Behavioral Therapy for Insomnia or control conditions over 16 weeks with 2-year follow-ups. Depression and insomnia severity were assessed at baseline, biweekly during treatment, and every 4 months thereafter. Sleep effort and beliefs about sleep were also assessed.

Results: Growth mixture modeling revealed three trajectories: (a) Partial-Responders (68.9%) had moderate symptom reduction during early treatment (p value < .001) and maintained mild depression during follow-ups. (b) Initial-Responders (17.6%) had marked symptom reduction during treatment (p values < .001) and low depression severity at posttreatment, but increased severity over follow-up (p value < .001). (c) Optimal-Responders (13.5%) achieved most gains during early treatment (p value < .001), continued to improve (p value < .01) and maintained minimal depression during follow-ups. The classes did not differ significantly on baseline measures or treatment received, but differed on insomnia-related measures after treatment began (p values < .05): Optimal-Responders consistently endorsed the lowest insomnia severity, sleep effort, and unhelpful beliefs about sleep.

Conclusions: Three depression symptom trajectories were observed among patients with comorbid insomnia and MDD. These trajectories were associated with insomnia-related constructs after commencing treatment. Early changes in insomnia characteristics may predict long-term depression outcomes. (PsycINFO Database Record

Trial registration: ClinicalTrials.gov NCT00767624.

Conflict of interest statement

The authors have declared all conflict of interest.

(c) 2018 APA, all rights reserved).

Figures

Figure 1

Estimated change trajectories for depressive symptoms for the three classes emerged from growth mixture models. Scores on the Hamilton Rating Scale of Depression do not include the sleep-related items to avoid overlapping items with insomnia. Shaded area indicates treatment period.

Figure 2

Means and 95% confidence intervals for the three classes on FIRST (Ford’s Insomnia to Stress Response Test) at baseline, ISI (Insomnia Severity Index), GSES (Glasgow Sleep Effort Scale), and DBAS (Dysfunctional Beliefs and Attitudes about Sleep Scale) at BL (baseline), MID (mid-treatment), and POST (immediately post-treatment); the ISI has an additional 2-year follow-up (FU).