Discrepancy between objective and subjective cognitive deficit is common among patients with major depressive disorders (MDDs) and may play a key role in the mechanism linking cognition with recovery of symptom and psychosocial function. This study, therefore, explores the cognitive discrepancy, and its association with the trajectory of symptoms and functioning over a 6-month period.

We used data from the Prospective Research Observation to Assess Cognition in Treated patients with MDD (PROACT) study, from which 598 patients were included. Cognitive discrepancy scores were computed using a novel methodology, with positive values indicating more subjective than objective deficit (i.e. ‘underestimation’) and negative values indicating more objective than subjective difficulties (i.e. ‘overestimation’). Linear growth curve models were employed to examine the association of the cognitive discrepancy with the trajectory of depressive symptoms, psychosocial function, and quality of life.

About 68% of patients displayed disproportionately more objective than subjective cognitive deficit at baseline, and the mean cognitive discrepancy score was −1.4 (2.7). Overestimation was associated with a faster decrease of HDRS-17 (β = −0.46, p = 0.002) and a faster decrease of psychosocial function in social life (β = −0.13, p = 0.013) and family life (β = −0.12, p = 0.026), and a greater improvement of EQ-5D utility score (β = 0.01, p < 0.001).

We found a lower sensitivity of cognitive deficit at baseline and its decrease was associated with better health outcomes. Our findings have clinical implications of the necessity to assess both subjective and objective cognition for identification and categorization and to incorporate cognitive and psychological therapies for optimized treatment outcomes.