The present study aimed to determine if anodic transcranial direct current stimulation (t-DCS) produces a significant increase in the mean flow rate of the middle cerebral artery in healthy subjects.

Stroke is a leading cause of death and disability caused by a disruption of blood flow that carries oxygen and glucose to neurons. The collateral circulation has become an attractive therapeutic target to improve blood flow to critical areas. t-DCS may enhance it, increasing blood flow to the penumbra area.

Twenty subjects were previously recruited to receive anodic t-DCS. They were randomly assigned to receive either sham or real anodic stimulation. Before and after t-DCS, a transcranial Doppler ultrasound (TCD) was performed to assess the blood flow of bilateral middle cerebral arteries. Delta values of middle cerebral arteries (post-stimulation mean velocity - pre-stimulation mean velocity) were calculated to assess changes in the arterial blood flow. The TCD was carried out by the research group, who was blinded with respect to the group of t-DCS to which each subject corresponded.

There were no significant differences of blood flow values in any of the measurements (left and right) between the pre-stimulation vs. post-stimulation analysis. The only potential effect was induced by anodic stimulation in the left M1 cortex, were a slightly increase in the mean velocity of both middle cerebral arteries was observed, without reaching a statistically significant difference.

The present study could not observe an increase in the flow rate of the middle cerebral artery. We suggest more studies with a larger number of subjects and carrying out different stimulation paradigms. We also suggest measuring the elapsed time from the end of t-DCS to the measurement of each of the arteries.