Cognitive function after clinical remission in patients with melancholic and non-melancholic depression: a 6 month follow-up study

Abstract

Background: Cognitive symptoms are core symptoms with an impact on functioning in depression. Remission is considered as the main objective of the management and treatment of depression. This study was aimed to compare cognitive performance between melancholic (MelD) and non-melancholic depression (NMelD) and to determine whether these cognitive alterations remain after clinical remission.

Methods: We performed a 6 month follow-up study of 88 melancholic and non-melancholic depressive patients. Sociodemographic and clinical characteristics were recorded. Depression was examined using the Hamilton Depression Rating Scale and the CORE Index for Melancholia. Cognitive performance was assessed with the Trail Making Test (TMT), the Digit Span subtest of the WAIS-III, Stroop Colour Word Test (SCWT), the Tower of London (TOL DX), the Controlled Oral Word Association Test (FAS), Semantic Verbal Fluency and Finger Tapping Test (FTT).

Results: MelD patients show worse performance than N-MelD at baseline, with significant differences at Digit Span subtest of WAIS Part I and Part II, SCWT Part I and Part II, TOL DX, Total Problem Solving, Total Execution Time and FTT- Preferred hand. Cognitive impairment remains at six months follow-up after clinical remission in MelD. In the comparison between remitted and non-remitted patients, cognitive impairment in Trail Making Test Part B and Verbal and Semantic Fluency (Animals) remains after clinical remission in MelD group but not in non-melancholic patients.

Limitations: The use of psychopharmacological treatment and the small sample of melancholic patients.

Conclusions: Patients with MelD do not improve cognitive performance despite clinical remission compared with remitted NMelD patients. The persistence of some cognitive dysfunctions in MelD remitted patients could represent a trait marker of a different depressive subtype and not be secondary to disease severity.

Keywords: Cognition; Depressive disorder; Melancholic depression; Remission.