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In 2003, prescriptions of depression medicines have grown by 40% in the U.S. in the previous two years.
Depression is typically treated with medication, psychotherapy or a combination of both. Medications include tricyclic antidepressants (TCAs), SSRIs and others. Not all patients respond to the same therapy and patients often try multiple therapies. Other treatments include light therapy and rarely, surgery.
Another alternative to depression medicines is the electro convulsive therapy (ECT). ECT typically involves general anesthesia and multiple treatments that can cost from $8,000 to as high as $20,000 per patient per year. Treatment morbidity associated with ECT includes the risks of general anesthesia, as well as short and long-term cognitive deficits, including memory loss.
Preliminary results from Cyberonics' of the Vagus Nerve Stimulator study suggest that the long-term use of vagus nerve stimulator therapy can produce improvements in depression. The positive results shown by the VNS Therapy trial for the long-term treatment of depression confirms that it offers the most effective solution for recurrent treatment resistant depression, over conventional depression medicines and ECT. The vagus nerve stimulator was originally approved for the treatment of epilepsy and is currently used by more than 18,000 epilepsy patients in 24 different countries. An estimated 4.5 million Americans suffer from chronic or recurrent treatment resistant depression versus 440,000 Americans with pharmacoresistant epilepsy.
The major advantages of the vagus nerve stimulator has over depression medicines is that it has a quick onset of action, a good side effect profile and is produced by the neuromodulation market leader. However, it does require invasive surgery. Although VNS is, at the present time, the only non-pharmacological treatment of depression, the development of less invasive methods, fewer side effects and improved efficacy is predictable.
VNS therapy is a proprietary, integrated system consisting of an implantable device that delivers an electrical signal to an implantable lead which is attached to the left vagus nerve. The vagus nerve is the longest of the cranial nerves, extending from the brain stem through the neck to organs in the chest and abdomen. The left vagus nerve has been shown to have influence over numerous areas of the brain. Preclinical studies and mechanism of action research suggest that intermittent stimulation of the left vagus nerve in the neck modulates a number of structures and alters blood flow bilaterally in several areas of the brain. These studies show that the stimulation of the left cervical vagus nerve is an effective alternative to conventional depression medicines.
Based upon the encouraging recent trial data and the growing requirement for novel alternatives to depression medicines, vagus nerve stimulator therapy is expected to receive good market uptake, if it gains FDA approval. VNS trials for other mental and neurological diseases, such as anxiety, obesity, migraine and Alzheimer are also underway. Although they are in their early stages with little data published to support any viable conclusions on the treatment's eficacy in these areas, there are hopes that the VNS therapy can become a viable alternative to pharmacological treatments just as it is for depression medicines.
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