BDNF genotype influence the efficacy of rTMS in stroke patients

Brain-derived neurotrophic factor (BDNF) genotype can influence neural response to repetitive transcranial magnetic stimulation (rTMS) in normal individuals. In this study we established personalized stimulus intensity of facilitatory rTMS according to BDNF genotype in stroke patients. Twenty-two chronic stroke patients were enrolled. All patients underwent three different sessions of rTMS over the ipsilesional M1 in randomized order with a washout period exceeding 24h: first condition, high-frequency rTMS with sub-threshold intensity; second condition, high-frequency rTMS with supra-threshold intensity; third condition, sham rTMS. Cortical excitability in the affected hemisphere was assessed with motor evoked potentials (MEPs) before and after stimulation. Data were analyzed according to BDNF genotype. Six [27.3%] and 16 [72.7%] participants were classified in the Val/Val group and Met allele group, respectively. In each group, significant increases were observed in the amplitude of MEPs after the stimulation in the first and second conditions (p<0.05), but not in the third condition. However, a significantly higher increase of amplitude of MEPs was observed between the first and second conditions in only the Val/Val group (p<0.05). BDNF genotype and stimulus intensity should be considered when high-frequency rTMS is used for the modulation of cortical excitability in patients with chronic stroke.