Motor excitability and motor behaviour after modafinil ingestion--a double-blind placebo-controlled cross-over trial

Modafinil is a novel vigilance-enhancing agent. We were interested if modafinil would also enhance motor excitability and improve motor performance and attention in healthy subjects. Ten volunteers received either a single oral dose of placebo or 200 mg modafinil. A randomized double-blind crossover design was used. Transcranial magnetic stimulation was employed to test intracortical inhibition, intracortical facilitation, the cortical silent period and to obtain stimulus-response curves. In addition, M responses and F waves were recorded. Reaction time tasks, the nine-hole-peg test and the d2 attention test were also applied. These studies were performed prior to and 3 and 24 hours after drug ingestion. Modafinil did not change excitatory or inhibitory properties in the motor cortex. It did not alter corticospinal excitability and alpha motoneuronal excitability. In the modafinil group and in the placebo group, performance of the nine-hole-peg test and the d2 test improved to a similar extend over time. Thus, this study does not demonstrate significant differences between a single dose of modafinil and placebo in healthy subjects.