Depression severity and concentration difficulties are independently associated with HRQOL in patients with unipolar depressive disorders

Purpose: Cognitive impairment is a core feature of major depressive disorder (MDD), and dysfunctions in this area strongly contribute to MDD-associated disability. Whether cognitive impairment has an independent clinical course and a unique impact on HRQOL is still debated. We sought to characterize the relationship between depression severity and HRQOL, evaluating the burden of concentration difficulties on HRQOL. Methods: Six hundred ninety-two patients with unipolar depressive disorders recruited in 19 Italian centers answered a self-administered survey (SF-12 questionnaire, socio-demographic information). A psychiatrist completed a standardized data collection form encompassing a depression severity scale (MADRS) and clinical information. Results: There was a strong graded association between the severity of depressive symptoms and both the physical (ω2 = 0.13; p < 0.01) and mental (ω2 = 0.34; p < 0.01) SF-12 domains. Additionally, we observed a strong association between concentration difficulties and all HRQOL outcomes independent of other symptoms of depression and robust to adjustment for possible confounders. Conclusions: Our data corroborate previous findings suggesting that cognitive impairment is a feature of unipolar depressive disorders partially independent of the severity of other symptoms, and may represent a specific target of therapy with a strong impact on patients’ functioning and quality of life.