0540 Insomnia Symptom Trajectories During and Following Combined Treatment for Insomnia and Depression: A Report from the Triad Study

Abstract Introduction Cognitive behavioral therapy for insomnia (CBT-I) reduces insomnia severity among individuals with insomnia and major depressive disorder (MDD). Understanding the long-term trajectories of insomnia symptom severity has the potential to inform optimization of CBT-I in this population. The objectives of this study were to examine trajectories of change in insomnia severity over a 16-week treatment phase and 2-year naturalistic follow-up, and explore correlates of symptom trajectories. Methods 148 adults (age 46.6±12.6, 73.0% female) with insomnia and MDD were randomly assigned to receive depression pharmacotherapy plus seven sessions of either CBT-I or control insomnia therapy. Depression and insomnia severity were assessed via the Hamilton Depression Rating Scale and Insomnia Severity Index at baseline, bi-weekly during treatment, and every 4 months over follow-up. Sleep effort and beliefs about sleep were assessed at baseline, midtreatment, and posttreatment. Results Latent class linear mixed modeling revealed four insomnia response trajectories: 1) Early Sustained-Responders (16%) showed marked improvement early in treatment, sustained over follow-up; 2) Gradual-Responders (36.7%) achieved substantial symptom reduction by posttreatment, sustained over follow-up; 3) Initial-Responders (25.3%) had substantial symptom reduction during treatment but increased in severity over follow-up; and 4) Partial-Responders (20.7%) achieved minimal improvement over treatment, and maintained moderate symptom severity over follow-up. Chi-square analyses revealed that classes did not differ significantly on sex, ethnicity, employment, relationship status, or treatment received (all ps > .05). One-way ANOVAs with Tukey’s HSD, showed that Partial-Responders consistently endorsed higher depressive symptom severity, sleep effort, and unhelpful beliefs about sleep at baseline, throughout treatment, and follow-up (ps < .05). Early Sustained-Responders endorsed lower sleep effort by midtreatment (ps < .01). Conclusion Results suggest four temporal patterns of treatment response and identified clinical correlates. Future work will be needed to determine if addressing sleep effort early in the course of treatment might enhance sustained insomnia outcome. Support MH078924, MH078961, MH079256