Changes of regional cerebral blood flow after repeated transcranial direct current stimulation in healthy participants: a pilot study

Background: Transcranial direct current stimulation (tDCS) can potentially enhance brain function and cognition in healthy individuals as well as in patients with cognitive impairment. However, neural correlates of repeated tDCS remain relatively unexplored in a healthy population. Purpose: To assess the effects of repeated tDCS on regional cerebral blood flow (rCBF) in healthy volunteers in a pilot investigation. Material and Methods: Five healthy adults received bifrontal tDCS to the dorsolateral prefrontal cortex (F3–F4 montage, 1 mA intensity, 30 minutes/session, five sessions/week) over four weeks. All participants underwent brain single-photon emission computed tomography (SPECT) scans at baseline and one week after the last tDCS session. Changes in rCBF were examined using Statistical Parametric Mapping. Results: Resting rCBF was significantly improved in the right superior frontal gyrus at the follow-up (P < 0.001). Adverse events were not reported and the stimulation was well-tolerated. Conclusion: Repeated tDCS may be effective for enhancing brain function in healthy participants. Larger sham-controlled studies should be performed to confirm our preliminary findings.