No effect of anodal tDCS on motor cortical excitability and no evidence for responders in a large double-blind placebo-controlled trial

BackgroundTranscranial direct current stimulation (tDCS) has emerged as a non-invasive brain technique. Most studies show that anodal tDCS increases cortical excitability. However, this effect been found to be highly variable.ObjectiveTo test the of on excitability and interaction two participant-specific factors may explain individual differences in sensitivity tDCS: Brain Derived Neurotrophic Factor Val66Met polymorphism (BDNF genotype) latency difference between anterior-posterior lateromedial TMS pulses (APLM latency).MethodsIn 62 healthy participants, over left motor cortex was measured before after at 2 mA for 20 min pre-registered, double-blind, randomized, placebo-controlled trial with repeated measures.ResultsWe did not find main tDCS, nor an predictors. Moreover, further analyses provide evidence existence responders non-responders.ConclusionThis study indicates reliably affect