Effect of multi-session trans-cranial direct current stimulation of dorsolateral prefrontal area on depression and drowsines in patients with multiple sclerosis

Multiple sclerosis (MS) is one of the most common diseases of the central nervous system with high prevalence in the world and Iran. The common complications of disease are depression and drowsiness. Due to structural and functional brain changes following depression and drowsiness in patients with MS, brain electrical stimulation may be considered as an effective intervention in therapy.

In this double blind clinical trial, 30 patients with MS were randomly divided into experimental and sham a-tDCS groups according to the inclusion and exclusion criteria. Correspondingly, the anode electrode was placed on the left dorsolateral prefrontal cortex (DLPFC) and cathode on the opposite supra orbital. In the experimental group, 20-minute DLPFC a-tDCS with intensity of 1.5 mA was performed during 10 sessions for 20 days with a one-day rest interval between sessions. However, in the sham a-tDCS group, although the electrodes were placed in the same positions as it used for the experimental group, the stimulation was slowly turned off after 30 seconds.

The results in the experimental group showed that the depression after intervention was significantly decreased as compared to before intervention (P<0.05), but there was no significant differences in the rate of drowsiness before and after the intervention (P>0.05), although the trend of drowsiness was toward reduction. Also, drowsiness and depression level were significantly improved after the intervention in experimental as compared to control group.

Multi-session a-tDCS over the left DLPFC have a significant effects on the improvement of depression and rate of drowsiness in patients with MS.