Behavioural and neurophysiological differences in working memory function of depressed patients and healthy controls

Stevan Nikolin*, Yi Yin Tan, Donel Martin, Adriano Moffa, Colleen K Loo, Tjeerd W. Boonstra

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

OBJECTIVE: Major depressive disorder (MDD) is associated with deficits in working memory. Several cognitive subprocesses interact to produce working memory, including attention, encoding, maintenance and manipulation. We sought to clarify the contribution of functional deficits in these subprocesses in MDD by varying cognitive load during a working memory task.

METHODS: 41 depressed participants and 41 age and gender-matched healthy controls performed the n-back working memory task at three levels of difficulty (0-, 1-, and 2-back) in a pregistered study. We assessed response times, accuracy, and event-related electroencephalography (EEG), including P2 and P3 amplitudes, and frontal theta power (4-8 Hz).

RESULTS: MDD participants had prolonged response times and more positive frontal P3 amplitudes (i.e., Fz) relative to controls, mainly in the most difficult 2-back condition. Working memory accuracy, P2 amplitudes and frontal theta event-related synchronisation did not differ between groups at any level of task difficulty.

CONCLUSIONS: Depression is associated with generalized psychomotor slowing of working memory processes, and may involve compensatory hyperactivity in frontal and parietal regions.

SIGNIFICANCE: These findings provide insights into MDD working memory deficits, indicating that depressed individuals dedicate greater levels of cortical processing and cognitive resources to achieve comparable working memory performance to controls.

Original languageEnglish
Pages (from-to)559-568
Number of pages10
JournalJournal of Affective Disorders
Volume295
Early online date31 Aug 2021
DOIs
Publication statusPublished - 1 Dec 2021

Keywords

  • Depression
  • Working memory
  • Electroencephalography
  • Event-related potentials
  • Frontal theta
  • EVENT-RELATED POTENTIALS
  • N-BACK
  • PSYCHOMOTOR RETARDATION
  • MAJOR DEPRESSION
  • INDIVIDUAL-DIFFERENCES
  • UNIPOLAR DEPRESSION
  • THETA OSCILLATIONS
  • EXECUTIVE FUNCTION
  • GENDER-DIFFERENCES
  • SIMULTANEOUS EEG

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