Brain derived neurotrophic factor negatively responded to transcranial direct current stimulation: randomized controlled trial

Abstract

Introduction: Brain-derived neurotrophic factor (BDNF) levels could indicate synaptic plasticity, modulation of BDNF might be a part of transcranial direct current stimulation (tDCS) mechanisms on synaptic connectivity [1]. BDNF associated with changes to chronic pain and stress [2]. The study aims to investigate BDNF level change in response to tDCS in subacute ischemic stroke patients. Clinical trial registration ID NCT04770363. Methods: 36 stroke survivors participated, randomly assigned to bihemispheric (Anodal over affected M1, and cathodal over healthy M1), or unihemispheric (Anodal over affected M1, and cathodal over supraorbital bone), or sham (No current). ActivaDose tDCS (USA), consisted of 20 minutes of 2 mA intensity; in each session for 12 sessions three per week. A 3ml blood was withdrawn in first and last sessions. BDNF determined using ELISA kits. Results: Statistically significant difference (Negative) within groups for bihemispheric (P = .011), unihemispheric stimulation (P = .003), but not for sham group (P = .492). Significant difference between groups (P = .005). Post-hoc test by pairwise revealed both bihemispheric & unihemisphericstimulation significantly decreased BDNF levels more than sham (P = .001), (P = .021), respectively and no significant difference between both experimental groups (P = .217). Discussion: Negative decrease in BDNF levels associated with positive improving of motor measures, and upper extremity pain relieving. Process Evaluation: Long-term effect of tDCS, electrode placements, and polarity change of electrodes should considered for future studies. Applying the same current intensity/dose for all participants was a critical limitation.