Treatment-resistant depression (TRD) affects 1-3% of the population. Recently Holtzheimer & Mayberg reviewed the effectiveness of a range of new and promising techniques based on direct neural stimulation. The list includes Transcranial magnetic stimulation, Transcranial direct current stimulation, Magnetic seizure therapy, Vagus nerve stimulation and Deep brain stimulation.

The prototype of course is ECT (electroconvulsive therapy), which is a highly effective treatment for melancholic depression, but suffers from the effects of a negative historical portrayal. The authors present a balanced and elegant appraisal of the current state of affairs for the new techniques which can be read here in full. The summary points are as follows…

Transcranial magnetic stimulation (TCMS)

– FDA (US food & drug administration) approved.

– Uses rapidly alternating magnetic fields to induce current in the underlying cortex.

– 10 to 30 treatment sessions over 2-6 weeks.

– Controlled trials have been positive.

– Response rates in TRD: 20-40%.

– Remission rates in TRD: 10-20%.

– Repeated courses may maintain initial benefits.

Transcranial direct current stimulation

– Delivers a low-intensity direct current to the underlying cortex.

– 5 times per week treatments for several weeks.

– Fewer side effects than TCMS?

– Antidepressant effects claimed from a small number of open and controlled studies.

– Response, remission & relapse rates are unclear.

Magnetic seizure therapy

– Seizures are induced using a transcranial magnetic stimulation device.

– Antidepressant effects from a small number of open studies.

– Claims for less side-effects than ECT, but may be less effective.

Vagus nerve stimulation

– FDA (US food & drug administration) approved.

– Electrical stimulation to the left vagus nerve through an implanted pulse generator.

– Open-label response rates in TRD: 30-40%.

– Open-label remission rates in TRD: 15-17%.

– No evidence for efficacy in a large controlled study.

– Simple surgical procedure.

Deep brain stimulation.

– Precise neurosurgical implantation of electrodes using stereotactic techniques.

– Remission rates in TRD: 40-60%.

– Relapse in remitted patients is uncommon.

– Complex surgical procedure.

Holtzheimer & Mayberg conclude, “Neuromodulation for depression is at an exciting and promising stage of development, and continued well-conducted research will help clarify and realize its potential“.