DBS changes uses implanted microstimulators to block abnormal nerve signals sent between brain structures, with the effect determined by the precise placement of the stimulators. Researchers have successfully used these so-called "brain pacemakers" to treat movement disorders like Parkinson's disease, and the new study seeks to confirm that they can help patients with OCD as well. The team will also attempt to determine exactly which brain network is disrupted in OCD in hopes of fine-tuning treatment.
OCD is a chronic anxiety disorder that affects 2.2 million Americans. Patients struggle with obsessions and the urgent need to repeat behaviors that can relieve anxiety. Sufferers may feel compelled to wash their hands or clean constantly with the hope of making obsessive thoughts go away, but such rituals provide only temporary relief.
"DBS is one of the most promising areas of OCD research because early studies show that it may help many within the approximately 20 percent of OCD patients for whom neither psychological nor drug therapy works," said Suzanne Haber, Ph.D., a professor within the Department of Pharmacology and Physiology at the University of Rochester School of Medicine and Dentistry. "Some patients have been able to venture out to work and school for the first time with DBS," said Haber, who is lead investigator for the grant.
The grant is funded through two institutes within NIH, the National Institute of Mental Health (NIMH) and the National Institute on Drug Abuse (NIDA). While NIMH will fund the majority of the project, NIDA also contributed because of the work's potential to further the understanding of addictions. OCD and drug addiction appear to engage some of the same brain regions involved in habit formation.
Study Details
Deep brain stimulation was approved by the U.S. Food and Drug Administration in 1997 for the treatment of epilepsy and Parkinson's disease. DBS involves implantation of microstimulators, similar to those used in heart pacemakers, in targeted brain regions to block the nerve signals believed to cause disease symptoms. In 2005, a study found that
DBS might also be useful against treatment-resistant clinical depression, opening the door for DBS treatment of severe psychiatric disorders. To date, about 25 OCD patients for whom other treatments have been ineffective have received DBS implants. The OCD studies, while small, have shown dramatic reductions in symptoms for many patients. The main focus of the new study is to understand the brain regions involved in OCD and to help determine the most effective pacemaker placement.
As part of the new grant, the medical center is partnering with Massachusetts General Hospital, Brown University and the University of Pittsburgh. The research group at the University of Pittsburgh will examine the underlying physiology to help understand how deep brain stimulation works. Teams at Massachusetts General and Brown will partner to conduct a small clinical study of OCD patients randomized to receive either DBS at different sites or no stimulation.
In the trial, treatment effectiveness will be assessed at the different points of stimulation. PET scans will be used to capture images of patients' brains during stimulation and without stimulation. PET scan technology measures changes in blood flow through the brain, with blood flow changes corresponding to changes in nerve networks within the regions under examination. Using these images, Haber will direct studies at the medical center that focus on the understanding the brain network involved in OCD to improve current treatment and suggest new treatment approaches. Past studies show that the most promising DBS target for OCD is the basal ganglia, a group of nuclei associated with movement and learning. More specifically, two brain structures within the basal ganglia: the ventral anterior internal capsule (VC) and the adjacent ventral striatum (VS) will be targeted for stimulator placement. Researchers believe these regions are at the intersection of many important nerve pathways related to OCD.
In the early 20th century, a surgical procedure called frontal lobotomy was used to treat severe psychiatric disorders. These approaches, while helpful, often blunted a patient's personality. The misuse of this procedure combined with its severe side effects gave it a bad reputation and ended its use. More precise psychosurgical procedures are still used for otherwise untreatable patients.
"Our research is part of a larger trend where researchers are seeking to replace older 'ablative' surgical techniques," Haber said. "These old methods, while bringing relief from a variety of debilitating diseases, also permanently destroy nerve circuits. Our hope is to use non-destructive procedures like DBS as a therapeutic approach for these devastating disorders."