The Assessment of Cognitive Dysfunction in Major Depressive Disorder: A 16-Week Prospective Case-Control Study

Cognitive dysfunction is one of the core components of major depressive disorder (MDD). It is estimated that two-thirds of patients diagnosed with MDD have cognitive deficits. Cognitive symptoms are pervasive and affect functioning in several domains. This 16-week prospective case-control study aimed to assess the change of mood and cognitive symptoms during treatment.

Ninety-eight patients with MDD and 113 healthy controls (HCs) participated in the study. The MDD group was evaluated 6 times (baseline, 2^nd, 4^th, 8^th, 12^th, and 16^th weeks). For mood symptoms, the Montgomery-Asberg Depression Rating Scale was used, and for neurocognitive functions, the Perceived Deficits Questionnaire-Depression was used, and the Digit Symbol Substitution Test was administered to both groups.

At baseline, compared with the HCs, the neurocognitive function of patients with MDD was worse. From the 8^th to the 16^th week assessments, in both neurocognitive tests, the cognitive functions of patients with MDD had improved. Despite this improvement and the patients achieving remission, the patients' cognitive performance did not improve to the level of the HC group at the 16^th week.

Our longitudinal research revealed that even though mood symptoms decreased and patients with depression did achieve symptomatic remission, their cognitive deficits perpetuated.