Suprathreshold repetitive transcranial magnetic stimulation elevates thyroid-stimulating hormone in healthy male subjects

Repetitive transcranial magnetic stimulation (rTMS) has been introduced as a new antidepressive treatment strategy. The mode of action by which the an tidepressive effect is brought about is not yet clear. Other antidepressive treatment strategies such as sleep deprivation are associated with an incr ease of plasma thyroid-stimulating hormone (TSH) levels that correlate with clinical improvement. In the present study, the effect of left prefrontal suprathreshold (120% of motor threshold) rTMS on TSH plasma levels of 19 he althy male subjects was investigated in comparison with subthreshold (80% o f motor threshold) and sham stimulation. Suprathreshold rTMS was followed b y a significant relative increase of TSH levels 10 and 60 minutes after sti mulation in comparison with subthreshold and sham stimulation. The more pro nounced effect of suprathreshold rTMS on TSH plasma levels might be importa nt for the determination of optimal stimulation parameters in the treatment of depressed patients.