Parkinson's disease surgery raises suicide risk

NEW YORK (Reuters Health) - Suicidal behavior is a potential risk of deep brain stimulation in patients with Parkinson's disease, suggest the results of a study published in the Journal of Neurology, Neurosurgery, and Psychiatry.

Dr. Gilles Fenelon, of CHU Henri Mondor, Creteil, France, and colleagues point out that despite a high incidence of depression, Parkinson's disease patients have an overall rate of suicide similar to or lower than that of the general population.

"Recently," they add, "concerns have been raised about a higher than expected frequency of suicide among patients undergoing subthalamic nucleus deep brain stimulation (DBS) for advanced Parkinson's disease."

DBS is a surgical procedure use to relieve the neurological symptoms of Parkinson's disease, such as tremor, rigidity, stiffness, slowed movement, and walking problems. The procedure is also used to treat essential tremor and other neurological movement disorders.

The procedure involves the implantation of a battery-operated device that electrically stimulates targeted areas in the brain that control movement - and block the abnormal nerve signals that cause the symptoms of Parkinson's disease. DBS is currently recommended only for patients whose symptoms can't be controlled by drugs.

Fenelon and colleagues reviewed the records of 200 Parkinson's disease patients who underwent subthalamic nucleus DBS between 1997 and 2006. The researchers observed that in spite of improved symptoms, two patients (1 percent) committed suicide and four patients (2 percent) attempted suicide, at an average of 12 months after surgery.

Suicidal patients and non-suicidal patients did not differ in age, disease duration, or preoperative depressive and cognitive status. However, an association was found between suicidal behavior and depression that developed along with an increase in impulsiveness after the surgery.

The authors point out that in a recent study of 5,025 Parkinson's disease patients who underwent subthalamic nucleus DBS, the rates of completed and attempted suicide were 0.4 percent and 0.9 percent, respectively, "which are again higher than in the general population."

"It should be emphasized that suicides have also been reported following pallidal or thalamic DBS in patients with Parkinson's disease and other conditions," Dr. Fenelon and colleagues added.

This suggests that a disturbance in these regions of the brain may induce mood disorders and suicidal thoughts.

In a related editorial, Dr. John Moriarty at King's College Hospital in London writes: "Patients may find it hard to accept that they might be at risk of killing themselves following surgery, even if good motor outcome is achieved and their movement disorder has responded well."

Moriarty predicts that most patients will still decide to have the surgery. Nevertheless," he concludes, "it seems clear that suicide, perhaps largely unpredictable, remains an important cause of mortality in patients undergoing surgery for movement disorders."

SOURCE: Journal of Neurology, Neurosurgery, and Psychiatry, August 2008.