Transcranial Magnetic Stimulation Therapy of Major Depressive Disorder Improves Heart Rate Variability

Transcranial magnetic stimulation is typically administered daily for 6 to 9 weeks with gradual resolution of major depressive disorder. However, there is little evidence to guide clinicians when clinical improvement is not forthcoming as the course proceeds. We describe a patient whose depression score remained unchanged after 10 single daily intermittent thetaburst transcranial magnetic stimulation sessions targeting F3 in the dorsolateral prefrontal cortex and our efforts to modify the technique and monitor progress with heart rate variability (HRV) measures. The motor threshold position and intensity were verified to be unchanged from the baseline visit. Stimulation of F3 and treatment target 6 cm anterior to the mapped motor cortex site seemed to slow heart rate and increase HRV equally. We increased the number of daily intermittent thetaburst pulse trains for the remainder of the treatment course, targeting the 6-cm target. Our patient subsequently improved, and we observed concurrent changes in HRV suggestive of enhanced parasympathetic activity. These improvements were found to be durable at 10-week follow-up.