The World Health Organization has projected that by 2020, major depression will be the second-most significant cause for disability in the world, after heart disease. Along with psychotherapy, the disorder is usually treated using antidepressant drugs. There is often a frustrating trial-and-error period involved in finding the right drug for the right person, however, while side effects can include obesity, sexual dysfunction, and fatigue ... to name a few. Los Angeles-based company NeuroSigma is now looking into an alternative drug-free therapy, that could ultimately incorporate electrodes implanted under the patient's skin.

In an eight-week clinical trial conducted last June, researchers at UCLA externally stimulated the cranial trigeminal nerve of patients who suffered from depression. This was accomplished by attaching two electrodes to the skin of each subject's forehead, which were in turn attached to a mobile phone-sized stimulating device. The external Trigeminal Nerve Stimulation (eTNS) process reportedly resulted in a 70 percent reduction in symptom severity during the trial, and a subsequent 80 percent remission rate, with none of the side effects associated with antidepressants.

The technology is licensed exclusively to NeuroSigma.

Last month, findings were presented on four more subjects from those trials, including functional neuroimaging PET data. It was determined that even brief exposure to eTNS increased blood flow to regions of the brain associated with depression and mood regulation. "These findings of a potential mechanism of action support our original hypothesis that electrical stimulation of the trigeminal nerves, located in facial skin tissue, can provide a very safe and effective means to send signals to key structures deep in the brain, thus providing a high-bandwidth pathway to the brain without current penetrating directly through the skull" said UCLA's Dr. Ian Cook.

A twenty-subject, double-blind second phase of the trials began this February, and should wrap up late this year.

NeuroSigma is meanwhile continuing development of eTNS, while also working on a version of the system that would utilize implantable subcutaneous electrodes. Known as sTNS, patients who responded well to eTNS could choose to switch over to it. The technology could also possibly be used to treat epilepsy and post-traumatic stress disorder.