Brain “Pacemaker” Triggers Impulsive, Irrational Behavior: Study

Deep brain stimulation, one of the most used means of treating Parkinson's disease may actually leave patients prone to impulsive behavior, a team of researchers from University of Arizona has shown.

A surgical treatment, deep brain stimulation (DBS) involves the implantation of a brain pacemaker- a device that electrically stimulates the movement-controlling part of the brain.

In the study researchers found that Parkinson's patients fitted with the device often showed an impulsive behavior that can be dangerous. However, when the brain stimulation was turned off, the Parkinson's patients with the devices acted totally normally, regaining their ability to think aptly under taxing circumstances.

Adding to the patient’s woes, while DBS may prove beneficial for some, there is a potential for neuropsychiatric side effects like apathy, compulsive gambling, hypersexuality, cognitive dysfunction, and signs of depression in other patients.

Parkinson's disease is a degenerative disorder of the central nervous system that often blights the sufferer's motor skills and speech.

Caused by the insufficient formation and action of dopamine- a chemical crucial for movement, when these cells are destroyed, patients experience tremors, muscle rigidity and walking and balancing problems.

"For Parkinson's patients, this study highlights the fact that there are side effects to most interventions. Even though patients know they have balance problems and are at risk for falling, they may still act impulsively. Patients may gain more mobility with deep brain stimulation, only to experience more falls, noted Dr. Scott Sherman, a neurologist at University of Arizona.

Unlike anti- Parkinson medications that stimulate dopamine production in brain, deep brain stimulation treatment targets a smaller area of the brain that affects motor skills. Unfortunately, this also conflicts decision-making, thus triggering impulsive, irrational behavior.

"But even with what we know about the impulsive behavior now, the effects of DBS treatment can be really amazing for patients and far outweigh the side effects. So this is not a reason to avoid the therapy. But as we understand how this affects the brain, we are more aware of what can happen, and we can make adjustments to benefit the patient's quality of life,” Sherman added.

The findings of the study feature in the journal Science.