The Role of Chronic Anhedonia in the Relationship Between Treatment-Resistant Depression and Suicidality.

Objective: Treatment-resistant depression (TRD) is a severe form of major depressive disorder (MDD) associated with increased suicidality. Anhedonia, the reduced ability to experience pleasure, is recognized across various psychiatric conditions, including TRD. This study aims to investigate the relationship between chronic anhedonia, or low hedonic tone, and suicidal behavior in patients with TRD. Methods: A cohort of 160 participants from the START Clinic for Mood and Anxiety Disorders in Toronto, Canada, was assessed. Diagnosis of TRD followed criteria established by McIntyre et al (2014) and used the Mini International Neuropsychiatric Interview (MINI) 6.0.0 diagnostic evaluation. Chronic anhedonia was classified using the MINI module A, and suicidality was assessed using the MINI Suicide Module. Results: Of the 160 participants, 97 met the criteria for TRD. Within the TRD group, 58% reported chronic anhedonia. Participants with TRD and chronic anhedonia were 2.4-fold more likely to report suicidal ideation (P=.049) and 3.9-fold more likely to report a suicide attempt (P=.035) in the preceding month than those without chronic anhedonia. Conclusion: Chronic anhedonia is significantly associated with an increased risk of suicidal ideation and attempts in patients with TRD. Clinicians should consider chronic anhedonia as a key risk factor for suicidality in this population and prioritize its assessment and management.