0974 Daytime Insomnia Symptoms Negatively Predict Anhedonia in Patients with Comorbid Major Depressive Disorder and Insomnia Disorder

Abstract

Insomnia is one of the most common, but difficult symptoms to treat in major depressive disorder (MDD), often persisting after depression has remitted and predicting poorer treatment response. Anhedonia, a core symptom of depression, also predicts poorer treatment outcomes. Co-occurring depression and insomnia present unique challenges for treatment. The present study aimed to clarify the relationship between anhedonia and insomnia in patients with comorbid MDD and insomnia disorder. Baseline data were collected as part of a multisite randomized controlled trial of CBT-I as an adjunct treatment to antidepressant medication in 150 adults with comorbid MDD and insomnia disorder. Structural equation modeling (SEM) was used to determine the relationship between insomnia symptoms and anhedonia. Objective sleep measures and subjective sleep and daytime symptoms of insomnia were tested as predictors of anhedonia. An Objective Sleep Disturbance latent variable was constructed using actigraphy and polysomnography Total Wake Time (TWT). A Subjective Sleep Disturbance latent variable was defined using sleep diary average TWT and PROMIS: Sleep Disturbance total score. A Daytime Symptoms latent variable was constructed using the Hamilton Rating Scale for Depression (HRSD) energy item and PROMIS: Sleep Related Impairment total score. The Anhedonia latent variable was defined using HRSD and Quick Inventory for Depressive Symptomatology anhedonia items. Fit statistics for the hypothesized SEM model were adequate (X2 = 17.95; df= 15; CFI= .897; TLI= .753; RMSEA= .037). Daytime Symptoms of insomnia negatively predicted anhedonia in adults with comorbid MDD and insomnia disorder (p< .001). Neither Objective nor Subjective Sleep Disturbance predicted anhedonia in this model. We observed a negative relationship between the severity of daytime insomnia symptoms and anhedonia, and no relationship between objective sleep indicators or subjective nighttime symptoms and anhedonia. Support (If Any):