Effects on pain and cognition of transcranial direct current stimulation over the dorsolateral prefrontal cortex in women with chronic migraine.

We compared the effects of one versus two daily sessions of anodal transcranial direct current stimulation (a-tDCS) delivered to the left dorsolateral prefrontal cortex (DLPFC) for 10 days in a cohort of 30 women (mean age 28.0±6.92) with chronic migraine (CM, disease duration: 37.8±48.41 month). Participants were randomly allocated to three groups: a-tDCS 1-s Group received one daily a-tDCS session; a-tDCS 2-s Group received two daily a-tDCS sessions; Group SHAM received one daily session with a simulated (placebo) current. All participants were assessed before, after and one month after treatment, using the Migraine Disability Assessment, Montreal Cognitive Assessment, d2 Test of Attention, Trail Making Test (part B), Sequence of Letters and Numbers of the Wechsler Adult Intelligence Scale - III, and Nine Hole Peg Test. We found no difference between groups in the cognitive measures and motor dexterity. However, after treatment, a significant decrease in migraine-related disability was found for the a-tDCS 1-s Group. For all variables, no cumulative effects were observed in a-tDCS 2-s compared to the a-tDCS 1-s Group. The study findings provide preliminary results for future clinical trials designed to compare different intervals between tDCS sessions in CM.