Therapy For Treatment-Resistant Depression

By Andy Chiou
Peoria Surgical Group
Approximately 20 million Americans currently suffer from depression; 4 million of them experience treatment-resistant depression (TRD), according to estimates published in Psychiatric Clinics of North America. TRD is defined as depression that doesn’t respond to four or more trials of antidepressant treatment.

Effective New Treatment
Depression is a disease that steals the very essence of its victims. But vagus nerve stimulation (VNS) therapy offers hope to some of these individuals crushed by depression that just won’t go away.

VNS therapy is an adjunctive, long-term treatment used for chronic or recurrent depression in people over age 18 who haven’t had adequate response to four or more treatments. Although many patients respond well to various medications, others don’t respond at all—or their treatments become less effective over time. However, VNS therapy has been shown to provide effectiveness that improves over time and lasts long term, significant and lasting improvement, mild to moderate side effects that typically decrease over time, and a unique safety profile.

This therapy has been studied since 1988, and the first clinical studies for chronic and recurrent depression began in 1998. It was FDA approved in 2005.

After one year, roughly one in three people receiving VNS therapy experienced significant mood improvements, compared with one in eight people receiving only other antidepressant treatments. Many patients who didn’t respond immediately to VNS therapy experienced improvement over time. Most people who responded to VNS therapy maintained improvement long term; for some, it reduces the need for antidepressant medications over time.

Another open-label study, published in the Journal of Clinical Psychiatry, discussed the long-term benefits of VNS therapy. It revealed that after two years of VNS therapy, in addition to other treatments, 42 percent of patients noticed a significant improvement in mood and 22 percent had almost no symptoms of depression. It also demonstrated that side effects usually are tolerable; four out of five people continued to receive treatment at the end of the two-year study.

How it Works
The vagus nerve connects the lungs, heart, and stomach to the brain stem. VNS therapy is delivered by a pulse generator (about the size of a small wafer cookie) and flexible wires that send mild pulses to the vagus nerve on the left side of the neck. These pulses are sent to specific areas of the brain that regulate mood, including those that affect the production or activity of neurotransmitters such as serotonin and norepinephrine. Activation of the left vagus nerve has been shown to induce widespread bilateral effects in the areas of the brain implicated in depression.

The procedure, which typically takes one hour and is performed under general anesthesia, is most often done on an outpatient basis. One small incision is made in the upper chest area for the pulse generator. Another small incision is made in the left neck for the wires that connect the generator to the vagus nerve; this is done in the natural folds of the neck, which helps hide the small scar. Although implanting the device is done by a specially trained vascular or general surgeon, the ongoing treatment and stimulations are performed by a qualified psychiatrist.

Generally, for depression therapy, the treating psychiatrist will adjust dosages of electrical currents in small increments. These dosage adjustments generally aren’t felt by patients. Similar to a pacemaker, the first stimulation is done two weeks after implantation. At that point, the psychiatrist will start adjusting the dosing using a handheld computer and telemetric wand; this can be done right in the psychiatrist’s office. The device sends signals regularly, 24 hours a day. It can take six months or longer to see changes and clinical results.

Another similarity to a pacemaker is that patients should be cautious around electrical or magnetic sources. Your physician will provide you with complete details, but it’s key to avoid MRI machines, large magnets, and radio transmitters (even those used in toys). You should remain at least one foot away from stereo speakers, arc welders, magnetic wands like those used at airports, cell phones, and battery-powered cordless tools such as drills.

Side effects
Common side effects, which only occur during stimulation, are mild to moderate and improve over time. These include temporary hoarseness/changes in voice tone, cough or tickle in throat, and a feeling of shortness of breath during exertion. If these side effects cause disruption to the patient’s day-to-day life, they can be managed with the use of a VNS therapy magnet. The individual simply places the magnet over the device to stop stimulation. Examples of when a patient may choose to do this include when making a speech or singing in public.

On the positive side, this treatment option sometimes allows patients to decrease the amount and number of medications needed, which could help minimize one of the most frustrating side effects of antidepressant medications: the reduction or elimination of sexual desire.

If you’d like to know more or are wondering if this option could help your treatment-resistant depression, talk to a psychiatrist who’s familiar with this treatment.  tpw