Elsevier

Brain Stimulation

Volume 7, Issue 2, March–April 2014, Pages 325-331
Brain Stimulation

Transcranial Direct Current Stimulation (tDCS)/Transcranial Alternating Current Stimulation (tACS)
Original Article
Concurrent Cognitive Control Training Augments the Antidepressant Efficacy of tDCS: A Pilot Study

https://doi.org/10.1016/j.brs.2013.12.008Get rights and content

Abstract

Background

Major depressive disorder (MDD) is frequently associated with underactivity of the dorsolateral prefrontal cortex (DLPFC) which has led to this brain region being identified as an important target for the development of neurobiological treatments. Transcranial direct current stimulation (tDCS) administered to the DLPFC has antidepressant efficacy, however the magnitude of antidepressant outcomes are limited. Concurrent cognitive activity has been shown to enhance tDCS induced stimulation effects. Cognitive control training (CCT) is a new cognitive therapy for MDD that aims to enhance DLPFC activity via behavioral methods.

Hypothesis

We tested the hypothesis that co-administration of DLPFC tDCS and CCT would result in a greater reduction in depressive symptomology than administration of tDCS or CCT alone.

Methods

27 adult participants with MDD were randomized into a three-arm sham-controlled between-groups pilot study comparing the efficacy of 2 mA tDCS + CCT, sham tDCS + CCT and sham CCT + 2 mA tDCS (5 sessions administered on consecutive working days). Blinded assessments of depression severity and cognitive control were conducted at baseline, end of treatment and a three week follow up review.

Results

All three treatment conditions were associated with a reduction in depression severity at the end of five treatment sessions. However, only administration of tDCS + CCT resulted in sustained antidepressant response at follow up, the magnitude of which was greater than that observed immediately following conclusion of the treatment course.

Conclusions

The results provide preliminary evidence that concurrent CCT enhances antidepressant outcomes from tDCS. In the current sample, participants receiving concurrent tDCS and CCT continued to improve following cessation of treatment. The clinical superiority of a combined therapeutic approach was apparent even in a small sample and following a relatively short treatment course.

Section snippets

Background

Because of its well-established neuromodulatory properties, transcranial direct current stimulation (tDCS) has been investigated as a therapeutic tool in psychiatry, with much of this work being done in major depressive disorder (MDD). Five open-label [1], [2], [3], [4], [5] and seven randomized sham-controlled investigations [6], [7], [8], [9], [10], [11], [12] have been conducted and all, but one [8], have described significant antidepressant effects. However, the results of two recent

Participants

Twenty seven acutely depressed adults participated in the study (10 female, 24 right-handed, mean age ± SD = 40.44 ± 14.52 years). All met criteria for a current DSM-IV defined Major Depressive Episode at study entry as confirmed by clinician administered interview with the Mini International Neuropsychiatric Interview [30]. While no minimum level of depression severity was required for study entry, baseline Montgomery Asberg Depression Rating Scale (MADRS) [31] scores ranged between 19 and 41,

Baseline demographics, clinical characteristics and cognitive performance

Participants in the three treatment groups did not differ significantly in age, number of year's education or estimated IQ (WTAR). No baseline group differences were observed in depression severity (MADRS), length of current depressive episode, number of prior episodes, age at initial depression onset, number of prior antidepressant medications trialed (Table 1) or baseline performance (reaction time or accuracy) on any version of the two-back task.

Clinical outcomes

One participant in the tDCS + CCT condition

Discussion

The current pilot study is the first investigation into whether administration of simultaneous cognitive training augments the therapeutic efficacy of tDCS for MDD. The results support the hypothesis that concurrent CCT potentiates antidepressant outcomes from anodal DLPFC tDCS. While five sessions of tDCS + sham CCT, sham tDCS + CCT and tDCS + CCT resulted in varying degrees of acute antidepressant efficacy, only the double active treatment condition was associated with ongoing antidepressant

Acknowledgments

We are extremely grateful to A/Prof Greg Siegle of Pittsburgh University, United States, for generously providing the CCT and PVT paradigms and associated technical assistance.

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  • Cited by (0)

    This study was made possible by funding received from Monash University, Department of Medicine, Nursing and Health Sciences and the National Health and Medical Research Council.

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