Action monitoring and depressive symptom reduction in major depressive disorder.

Introduction: Action monitoring has been reported to be disturbed in Major Depressive Disorder (MDD). Well-known markers for this action monitoring process are the error negativity/error-related negativity (Ne/ERN) and error positivity (Pe), both event-related potentials (ERP) generated in the anterior cingulate cortex. This study aims to explore the impact of symptom severity reduction on the Ne/ERN and Pe in MDD.

Methods: Behavioural and ERP measurements were obtained in 15 MDD patients during performance on a speeded flankers task during the early stages of a depressive episode and compared with those recorded after 7 weeks of treatment. The same schedule was used in 15 healthy controls.

Results: Whereas overall Ne/ERN and Pe peak amplitudes did not improve from sessions 1 to 2 in the patients, positive correlations emerged between between-session changes in symptom severity and Ne/ERN amplitudes. No such correlations were observed for the Pe. ERP amplitudes in the controls also remained unchanged between both sessions. Significant group differences were observed between MDD patients and controls for the Pe, but not for the Ne/ERN.

Conclusions: Whereas a clear association was observed between the level of symptom reduction and the level of improvement in Ne/ERN amplitudes in a MDD sample, no overall Ne/ERN enhancements were observed during symptom remission. Subsequent research is needed to further investigate the possible impact of depressive symptom reduction on the action monitoring in MDD. Several factors that might explain the absence of Ne/ERN group differences between patients and healthy controls in the current sample will also be discussed.