Doctors use deep brain stimulation for depression to determine whether certain parts of a person's brain can be stimulated to improve his or her mood. Electric pulses to the brain affect the chemistry of the brain, and researchers have looked into exactly how deep brain stimulation improves mood. Different parts of the brain have been stimulated in experiments, including the nucleus accumbens, the habenula and the subgenual prefrontal cortex. Researchers have tried to determine which part of the brain should be stimulated in order to get the best results.
Deep brain stimulation is the process of implanting electrodes in the parts of the brain that affect mood, then transmitting electrical impulses through these electrodes. The electrical impulses are controlled by a device similar to a pacemaker that is implanted underneath the skin of the patient’s chest. A wire connects the device, called a pulse generator, to the electrodes in the brain.
Although deep brain stimulation has been approved in many countries treat Parkinson’s disease, deep brain stimulation for depression is a more recent development. Many people with Parkinson’s disease who underwent deep brain stimulation reported improved mood, leading to studies that have tried to confirm that deep brain stimulation is a safe, effective treatment for severe depression. Research also has been done on the effectiveness of deep brain stimulation for obsessive-compulsive disorder and Tourette’s syndrome.
Deep brain stimulation for depression is used as a last resort, when depression is very severe and has not responded to more traditional treatments such as psychotropic medications or talk therapy. Doctors do extensive psychological and physical testing to ensure that a patient is a good candidate for a clinical trial of deep brain stimulation for depression. Patients qualifying for trials typically have very severe depression and are often unable to work or complete daily activities.
Preparing for deep brain stimulation for depression involves both brain surgery and chest surgery to implant the necessary devices. For the brain surgery, the medical workers give the patient local anesthetic, then drill holes in both sides of the skull to place the electrodes. For chest surgery, general anesthesia is used to put the patient to sleep, then the pulse generator is implanted near the collarbone. The pulse generator is usually activated after about a week, giving the patient time to recover.
As with any surgery, there are risks involved. Complications of surgery might include bleeding in the brain, stroke, heart problems, infection, speech problems and breathing problems. Also, the chest surgery has to be repeated every six to 18 months to replace the battery in the pulse generator. Side effects of the deep brain stimulation itself might include seizure, infection, depression, mania, insomnia and slight paralysis.