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Brain device
shows promise
(May
2005 Issue)
By Ami Albernaz
A pacemaker-like device that has been used for the past decade
to help relieve the symptoms of Parkinson's disease is continuing
to show promise in treating psychiatric disorders including obsessive-compulsive
disorder and severe depression.
In a recently completed study at Butler Hospital in Providence,
R.I. to be published later this year, deep brain stimulation, or
DBS, showed "meaningful clinical benefit" in roughly half of a small
sample of patients with intractable obsessive-compulsive disorder
(OCD), says Benjamin Greenberg, M.D., Ph.D., chief of outpatient
services at Butler and the leader of the study.
He says the study has also given researchers a greater understanding
of how the procedure works and encouragement for a future, larger-scale
study.
DBS has been touted in recent years as a potentially revolutionary
treatment for Tourette's disorder, epilepsy, cluster headaches and
some addictive disorders, as well as OCD and severe depression.
In DBS, electrodes are embedded in the anterior limb of the internal
capsule of the brain, an area linked to the circuitry of obsessive-compulsive
disorder. The electrodes are connected by wires to a battery pack
implanted in the patient's chest and which emits a high frequency
current that can be adjusted or turned off.
While researchers are not sure why applying electrical current
seems to bring some relief to some OCD patients, studies are enabling
the researchers to target the circuitry more precisely, Greenberg
says.
"We believe we have improved the technique through small differences
in the target," he says. "Just a few millimeters can make a big
difference."
A great advantage of DBS, Greenberg adds, is that unlike other
psychiatric surgical procedures, it is reversible. The device can
be removed and the current can be adjusted to optimize benefits
and minimize side effects.
Some of the patients in the Butler study whose OCD symptoms were
not helped by DBS did show improvement in mood - which is significant,
as depression frequently co-occurs with OCD, he says. DBS has also
shown promise among patients with severe depression (without OCD)
in trials in Cleveland, Ohio and Toronto, Ontario.
G. Rees Cosgrove, M.D., chief of neurosurgery at Lahey Clinic in
Burlington, Mass. is hoping to begin a trial in Massachusetts.
"I think [DBS] will have more relevance and use in severe depression
than in OCD," Cosgrove says, adding that depression is usually easier
to treat. Among OCD patients who have undergone DBS, he says, mood
improved before the OCD symptoms did.
DBS is an option only for patients whose symptoms have not responded
to other treatments. As a result, Cosgrove says, it is likely to
remain experimental at least for the foreseeable future.
"It will be a slow, ponderous progression," he says. "That's the
only responsible way to do it."
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