Impact of transcranial direct current stimulation on sustained attention in breast cancer survivors: Evidence for feasibility, tolerability, and initial efficacy

Abstract

Background: A significant subset of breast cancer survivors experience cognitive difficulties in attention and memory, which persist for years following treatment. Transcranial direct current stimulation (tDCS) has been shown to be effective in improving working memory, attention, processing speed, and other cognitive functions in both healthy and clinical populations. To date, no studies have examined tDCS for rehabilitation of cancer-related cognitive dysfunction.

Objective/hypothesis: We aimed to provide preliminary evidence for feasibility, tolerability, acceptability, and efficacy of tDCS in improving performance on a measure of sustained attention.

Methods: In a within-subjects design, 16 breast cancer survivors underwent 2 consecutive days of active tDCS over the prefrontal cortex, and 2 days of sham tDCS, counterbalanced for order of stimulation condition, while performing a continuous performance test.

Results: Stimulation was feasible and tolerable, with 89% of participants completing all sessions, and none reporting more than mild to moderate discomfort. Analyses of efficacy showed that during active stimulation, participants had significantly lower standard errors of reaction times overall, indicating better sustained attention ability, as compared to sham stimulation (p < 0.05). Furthermore, the effect of stimulation on standard errors of reaction times differed by inter-stimulus interval (ISI): for 1 and 2 s ISIs, there was no significant difference in performance between sham and active tDCS conditions, but for 4 s ISIs, stimulation improved variability in response times relative to sham (p < 0.05).

Conclusions: Results suggest that tDCS is feasible, tolerable, and may be an effective intervention to improve sustained attention difficulties in survivors with cancer-related cognitive dysfunction.

Keywords: Breast cancer; Cancer-related cognitive dysfunction; Sustained attention; tDCS.

Conflict of interest statement

All authors have confirmed that they have no conflict of interest to disclose.

Copyright © 2020. Published by Elsevier Inc.

Figures

Fig. 1.

tDCS montage with modeled current density for left dlPFC stimulation.

Fig. 2.

Stimulation did not have a significant effect on predicted mean standard errors of reaction times for 1s and 2s ISIs, but active stimulation significantly decreased variability in reaction times at 4s ISIs relative to sham. *p

Fig. 3.

Stimulation did not have a significant effect on predicted mean reaction times for 1s and 2s ISIs, but active stimulation marginally decreased reaction times 4s ISIs relative to sham, ‡p = 0.0565. Error bars represent standard errors of the means.