Cognitive Considerations in Major Depression: Evaluating the Effects of Pharmacotherapy and ECT on Mood and Executive Control Deficits

Abstract

Deficits in the executive control of attention greatly impact the quality of life of patients diagnosed with major depressive disorder (MDD). However, attentional deficits are often underemphasized in clinical contexts compared with mood-based symptoms, and a comprehensive approach for specifically evaluating and treating them has yet to be developed. The present study evaluates the efficacy of bifrontal electroconvulsive therapy (ECT) combined with drug therapy (DT) in alleviating mood-related symptomatology and executive control deficits in drug-refractory MDD patients and compares these effects with those observed in MDD patients undergoing DT only. The Hamilton Rating Scale for Depression and the Lateralized Attentional Network Test-Revised were administered across two test sessions to assess treatment-related changes in mood-based symptoms and conflict processing, respectively, in patients undergoing ECT + DT (n = 23), patients undergoing DT (n = 33), and healthy controls (n = 40). Although both groups showed an improvement in mood-based symptoms following treatment and a deficit in conflict processing estimated on error rate, a post-treatment reduction of an executive control deficit estimated on RT was solely observed in the ECT + DT patient group. Furthermore, Bayesian correlational analyses confirmed the dissociation of mood-related symptoms and of executive control measures, supporting existing literature proposing that attentional deficits and mood symptoms are independent aspects of MDD. The cognitive profile of MDD includes executive control deficits, and while both treatments improved mood-based symptoms, only ECT + DT exerted an effect on both measures of the executive control deficit. Our findings highlight the importance of considering the improvement in both mood and cognitive deficits when determining the efficacy of therapeutic approaches for MDD.

Keywords: attention; electroconvulsive therapy; major depression.

Figure 1

Sequence of events in an invalid cue/congruent trial as implemented by the Lateralized Attention Network Test-Revised (LANT-R) [29,44].

Figure 2

Comparison of HAMD scores in (1) HC vs. ECT + DT group; (2) HC vs. DT group; (3) ECT + DT vs. DT group. ** p < 0.001.

Figure 3

The Group × Session ANOVAs estimated on the CE (RT), with panel (1) showing the comparison between HC and ECT + DT, panel (2) showing the comparison HC vs. DT, and panel (3) showing the comparison between ECT + DT and DT, and subsequent Session × Cluster ANOVAs conducted separately for the ECT + DT (panel (4)) and DT (panel (5)) clusters. * p < 0.05; ** p < 0.01. ♦ indicates outlier.

Figure 4

The significant Group × Conflict interaction observed in the Bayesian ANOVA on error rate showed that both the ECT + DT and DT groups made significantly more errors compared with the HC group at pretest, while this difference was significant at post-test only in the DT group. (1) Comparison between the HC and ECT + DT groups, (2) comparison between the HC and DT groups, (3) comparison between the ECT + DT and DT groups. * p < 0.01, ** p < 0.001. ♦ indicates outlier.