An Integrated Sleep and Reward Processing Model of Major Depressive Disorder.

Major depressive disorder with comorbid sleep disturbance has been associated with negative outcomes, including lower rates of treatment response and a greater likelihood of depressive relapse compared to those without sleep disturbance. However, little, if any, research has been conducted to understand why such negative treatment outcomes occur when sleep disturbance is present. In this conceptual review, we argue that the relationship of sleep disturbance and negative treatment outcomes may be mediated by alterations in neural reward processing in individuals with blunted trait-level reward responsivity. We first briefly characterize sleep disturbance in depression, discuss the nature of reward processing impairments in depression, and summarize the sleep/reward relationship in healthy human subjects. We then introduce a novel Integrated Sleep and Reward model of the course and maintenance of major depressive disorder and present preliminary evidence of sleep and reward interaction in unipolar depression. Finally, we discuss limitations of the model and offer testable hypotheses and directions for future research.

Directionality of change in obsessive compulsive disorder (OCD) and suicidal ideation over six years in a naturalistic clinical sample✰.

BACKGROUND: Obsessive compulsive disorder (OCD) is associated with elevated suicide risk, but the directionality of the association between OCD severity and suicidal ideation has not been established, which was the goal of this study. METHODS: Participants (n = 325) were adults with either a current or past diagnosis of Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) OCD who were assessed annually for suicidal ideation and OCD symptom severity for six years. Cross-lagged panel analyses statistically compared unidirectional and bidirectional models over time. Serious suicide-related adverse events were reported. RESULTS: The best-fitting and most parsimonious model included paths predicting suicidal ideation from OCD symptom severity, but not vice versa. These results were confirmed by comparing a model with cross-lagged paths constrained equal to a freely estimated model. Higher OCD symptom severity in a given year was associated with a higher suicidal ideation severity in the subsequent year. Five suicide-related adverse events were reported throughout the duration of the study, including two suicide deaths and three suicide attempts. LIMITATIONS: The study relied on a single-item, annual measure of suicidal ideation in adults, with substantial variability in severity of suicide risk, and missing data increased with later observations in the study. DISCUSSION: OCD symptom severity predicted next year suicidal ideation severity. In contrast, suicidal ideation severity in a given year did not predict next-year OCD symptom severity in this OCD sample. Thus, rather than waiting for suicidal ideation to resolve, clinicians should consider providing empirically supported treatments for OCD.