Deep brain stimulation helps improve memory in patients with psychiatric illness

Researchers from the Cleveland Clinic will present results of a study that shows deep brain stimulation (DBS) is associated with improvements on formal memory tests in patients with severe psychiatric illness.

Since 2001, this team of investigators has been using DBS for treatment of obsessive compulsive disorder (OCD). At the 2006 American Association of Neurological Surgeons (AANS) Annual Meeting, they presented findings which demonstrated that DBS results in significant improvement in mood as well as reductions in anxiety, obsessions and compulsions in patients with both OCD and treatment resistant depression (TRD).

The results of the current study, DBS in the Internal Capsule/Ventral Striatum Improves Memory in Patients with Severe Psychiatric Disorders, will be presented by Cynthia S. Kubu, PhD, 3:00 to 3:15 p.m. on Monday, April 16, 2007, during the 75th Annual Meeting of the AANS in Washington, D.C. Co-authors are Hooman Azmi, MD, Benjamin Greenberg, MD, PhD, Donald Malone, MD, Andre Machado, MD, PhD, Gerhard Friehs, MD, Steve Rasmussen, MD, Paul Malloy, PhD, and Ali R. Rezai, MD. “Given the positive patient outcomes in our earlier research, the team decided to undertake a new study analyzing the effects of DBS on the cognitive symptoms of patients with severe psychiatric disorders,” stated Dr. Kubu.

An estimated 26.2 percent of Americans ages 18 and older – about one in four adults – suffer from a diagnosable mental disorder every year, which equates to approximately 57.7 million adults. While mental disorders are widespread, severe psychiatric illness affects a much smaller number of people – about 6 percent, or 1 in 17. Mental illness can affect the functioning and thinking processes of those who suffer, making daily tasks that most people take for granted, very difficult, if not impossible.

DBS has been used to treat intractable pain for several decades. More recently, use of this technology has proven to be a safe and highly effective treatment for tremor and Parkinson's disease with more than 35,000 DBS implants worldwide. The applications for DBS therapy are expanding rapidly.

DBS involves the placement of small electrodes into deep brain structures for the treatment of a variety of neurological and neuropsychiatric disorders. The electrodes are connected via wires to an internal pulse generator (IPG) that is placed in the chest wall. A magnet is used with the IPG to adjust the stimulation parameters so that the appropriate level of stimulation is applied at the electrode tip. The procedure is comparable to that of a cardiac pacemaker in which the pacemaker helps maintain an appropriate cardiac rhythm. DBS is presumed to help modulate dysfunctional circuits in the brain so that the brain can function more effectively. DBS has several advantages over other neurosurgical procedures in that the stimulation parameters can be adjusted to minimize potential side effects and improve efficacy over time. Furthermore, the treatment is reversible.

This research reports preliminary cognitive findings based on a series of 18 patients with severe psychiatric disorders (OCD n = 10, TRD n = 8) who underwent placement of bilateral deep brain stimulating electrodes near regions known to be important to emotional behavior. These regions of the brain also contain fiber pathways that are known to be important to different aspects of thinking (e.g., planning, attention, memory). All patients completed detailed testing measuring a variety of thinking skills prior to and following surgery.

Significant improvements in the recall of prose passages were observed following DBS in the internal capsule/ventral striatum. Furthermore, these improvements were not related to the concomitant improvements observed in the patients' underlying psychiatric disorders. Thus, the improvements in memory do not appear to simply reflect improvements in mood or OCD symptoms. No statistically significant declines in thinking skills were observed following DBS in this region.

“The placement of DBS electrodes in specific motor and psychiatric circuits in the brain has been shown to result in significant improvements in the underlying movement or psychiatric disorder symptoms. Our current findings suggest that DBS may also interface with memory circuits in the brain and result in improvements in memory function in patients with severe psychiatric disorders,” stated Dr. Kubu. “Clearly, these findings need to be replicated and more studies are planned to further understand the results,” added Dr. Kubu.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,800 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system, including the spinal column, spinal cord, brain and peripheral nerves.

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