Deep brain stimulation studied for depression, other disorders
Published: Wednesday, March 21, 2012, 12:02 AM
What if treatment were available that would work directly on the neurons in the brain, in effect jamming their circuits to relieve debilitating symptoms of depression?
One option might be deep brain stimulation.
“It’s just in the experimental stages, but right now, it has a lot of promise,” said Dr. Stephen Powers, referring to the use of DBS as a treatment for depression.
Used to treat movement disorders since the late 1990s, deep brain stimulation involves implanting electrodes into the brain through which electrical impulses are sent to block or modify the firing of the neurons that cause the problems. The amount of stimulation is externally controlled by a pulse generator, a pacemaker-like device placed under the patient’s skin in the upper chest.
Powers, now president of the Pennsylvania Neurosurgery and Neuroscience Institute Inc. in Lower Paxton Twp., was among the first neurosurgeons in Pennsylvania to use deep brain stimulation when he worked at Penn State Milton S. Hershey Medical Center in 1997. It is currently approved for use on Parkinson’s disease, uncontrollable movements called benign essential tremors and primary dystonia, a birth defect where a person has uncontrollable twisting of a body part.
For Parkinson’s patients, it has transformed lives by giving them tremor control and other relief from symptoms. “It works dramatically well, like throwing a switch,” said Dr. James McInerney, a neurosurgeon who specializes in deep brain stimulation at Hershey Medical Center.
These positive results have researchers eyeing the procedure for depression, epilepsy, stroke and more, although its use for the other disorders is in experimental stages only.
“The potential for DBS is close to unlimited,” McInerney said.
Psychiatric applications of deep brain stimulation show great promise, doctors said. It is already approved by the Food and Drug Administration for use in obsessive compulsive disorder on a “humanitarian device exemption” meaning it may only be done at certain institutions that establish a review board to supervise clinical testing.
Though there have been a handful of published studies in the last seven years on its use for depression, the number of patients involved is small, so there is still much research to be done, Powers said.
He said the research looked at two areas of the brain that are associated with behavior. “The studies found that DBS is safe and some patients got significantly better and could return to work,” Powers said. However, there is a caveat: Some patients entered an abnormal mental state known as hypomania and two committed suicide.
“There is still work to be done. The real concern is that by affecting an individual’s behavior like this, you may be somehow doing mind control,” said Powers, who noted that deep brain stimulation got its start in the early 1970s when it was first used to treat pain disorders. The societal atmosphere of the early ‘70s led to fears of government intrusion into individual’s lives and so DBS was dropped for about 20 years, he said.
Unlike the lobotomy, an irreversible procedure that interrupted abnormal pathways in the brain by cutting the connection, DBS is not destructive and can be undone simply by stopping its use, McInerney said. “It’s actually a restorative procedure and it’s done on a much more targeted area of the brain,” he said.
Though FDA approval is expected, McInerney said the FDA admits difficulty in assessing DBS for depression because it is hard to qualify its application for “quality of life” vs. concrete usage for something like tremor control in Parkinson’s disease.
“Many people in this country are on anti-depressants and most would not be a candidate for DBS,” McInerney said. “This would be for people being hospitalized for depression — the extreme sufferers who are at high risk for suicide.”
Aside from depression, DBS is expected to win FDA approval for use in epilepsy, doctors said. For epilepsy, a special response neuro stimulator with closed loop programming allows for information exchange between the brain and the programming unit to control the needed stimulation signal, Powers said. It has shown a 50 percent reduction in seizures, he said.
Deep brain stimulation also shows promise for another problem that is fast becoming a national health crisis — obesity.
“We’re not sure how it works. It may speed up the metabolism by stimulating different parts of the brain or work on the reward center,” McInerney said.
Use of DBS on brain injury from stroke is hard to qualify because everyone’s injury can be so different, but doctors say research is ongoing.
“It has been tried for severe head injuries where people are in a vegetative or minimally responsive state and they have become more interactive. While it has not brought them back to normal, it has improved their rehabilitative outlook,” McInerney said.
The cost effectiveness of deep brain stimulation for all these things has yet to be proven, doctors said.
For example, the standard DBS treatment for Parkinson’s requires $40,000 in hardware and $14,000 in a battery pack that must be replaced every three years over the patient’s lifetime, so it is an expensive treatment, Powers said.
If approved for depression use, the key would be in narrowing criteria for use or else insurance companies would likely not cover it, McInerney said.
However, he added, “for those extreme sufferers, it might be cheaper than ongoing hospitalizations over an indefinite number of years.”
Written by CAROLYN KIMMEL For The Patriot-News