During the past decade, it has emerged that cognitive dysfunction is a common and persistent disturbance in many adults affected by major depressive disorder (MDD).1 Indeed, aspects of cognitive functions have been a criterion item within the polythetical list of a major depressive episode (MDE) for several Diagnostic and Statistical Manual (DSM) iterations. Difficulties in concentration, thinking, and decision making have been the specific item(s) within the MDE criteria. Notwithstanding the common occurrence of cognitive dysfunction in MDD, the emphasis has historically been on “emotional” (eg, depressed mood) and “physical” (eg, disturbance in energy) symptoms.
The availability of a disparate assortment of psychotropic medications, manual-based psychotherapies, and neuromodulatory approaches, as well as a variety of innovative/investigational approaches (eg, ketamine, cognitive remediation), have provided clinicians and patients with a surfeit of opportunities to mitigate symptoms, and therefore improve patient function and integration. Available evidence, however, indicates that the vast majority of individuals receiving the forgoing treatments as part of an integrated care model still do not achieve patient-reported outcomes (PROs) that are prioritized as therapeutic objectives (eg, full functional recovery).3 For example, most individuals achieving symptomatic remission continue to evince psychosocial impairment and workplace disability. The failure to achieve both symptomatic and functional objectives has provided the impetus for identifying determinants of health outcomes in adults with MDD. This pursuit has resulted in the identification of cognitive dysfunction as a critical mediator of health outcomes for many adults with MDD.
Results from epidemiological and clinical studies indicate that disturbances in cognitive functions in adults with MDD are the most robust predictor of functional recovery amongst individuals in the community and post-discharge from hospitalization.4,5 Results from the International Mood Disorders Collaborative Project indicate that amongst adults (ages 18-65) who are gainfully employed (ie, greater than/equal to 20 hours of employment, schooling, volunteering per week), self-reported measures of cognitive dysfunctions are a more powerful determinant of workplace attendance and participation than is total depression symptom severity.6 The forgoing finding provides rationale for asserting that cognitive dysfunction in depression is a primary therapeutic target which should be screened for and measured.