Transcranial Direct Current Stimulation (tDCS) to Improve Fatigue and Cognitive Function

Fatigue and cognitive impairment are commonly reported symptoms associated with impaired quality of life (QOL) and productivity in breast cancer patients receiving chemotherapy. Working memory, the brain's system for temporarily storing and manipulating information required to carry out more complex cognitive tasks, is particularly affected by cancer and its treatment. In women who have undergone chemotherapy for breast cancer, neuroimaging studies show structural brain changes as well as functional inefficiencies in a region critical for working memory, the left dorsolateral prefrontal cortex (DLPFC). Fatigue appears to play a critical role in the recruitment of the DLPFC during cognitive tasks. Transcranial direct current stimulation (tDCS) is a safe, portable, non-invasive form of electrical brain stimulation that enhances neuronal transmission beneath scalp electrodes. Our group and others have shown that when applied to the left DLPFC, tDCS improves energy in patients with fatiguing medical conditions and that it improves cognition in both healthy adults and those with neurodegenerative diseases. The proposed feasibility trial is a randomized, sham-controlled, double-blind experiment. Eligible individuals will be ≥ age 18 years with stage I-IV breast cancer undergoing docetaxel-based chemotherapy every 3 weeks (at least 60 mg/m2 dose) with or without HER2-targeted therapy who self-report moderate or severe fatigue (rated ≥ 4 on a scale of 0-10) during at least 3 days of their most recent chemotherapy cycle. Participants will be randomized to either active or sham tDCS and will undergo 5 consecutive treatments of daily tDCS beginning the Monday following the first day of their on-study chemotherapy cycle. Active treatment will consist of a mild electrical current (2mA) administered via saline-soaked sponge electrodes placed along the intact scalp for 30 minutes a day for five days. Sham stimulation will involve brief delivery of current in a manner that does not result in changes in neuronal firing patterns, but that is perceived as active treatment by participants. Participants will complete self-report measures of fatigue, cognitive function and QOL along with cognitive testing at the beginning and end of the five-day intervention. Subjective fatigue, QOL and cognitive function will be also assessed prior to administration of the next cycle of chemotherapy. Total time on study will be approximately 3 weeks (one cycle of chemotherapy). Daily subjective fatigue will be monitored throughout participation.