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

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.

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.

There was a strong graded association between the severity of depressive symptoms and both the physical (ω ² = 0.13; p < 0.01) and mental (ω ² = 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.

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.