Researchers at the University of Iowa have conducted a study that sheds light on the cognitive and behavioral side effects of deep brain stimulation (DBS) in patients with Parkinson's disease. The study reveals that DBS, a treatment that helps alleviate motor symptoms such as tremors, may also affect patients' ability to shift their attention between tasks.

The subthalamic nucleus, a pea-sized region in the brain involved in motor control, has been targeted for DBS to control Parkinson's symptoms. It is believed that the overactivity of this brain region contributes to motor deficiencies in Parkinson's patients. However, researchers were curious whether the subthalamic nucleus also plays a role in thoughts and impulse control.

Deep brain stimulation involves a rhythmic generation of electrical signals by an implanted electrode in the subthalamic nucleus, which loosens its braking effect on movement, allowing for better motor control. While this technique has proven effective in controlling motor symptoms, some patients have experienced difficulties in focusing attention and controlling impulsive thoughts, leading to risky behaviors.

Jan Wessel, an associate professor at the University of Iowa, and his team designed an experiment to investigate the impact of DBS on attention shifting. Parkinson's patients participating in the study were asked to focus on a computer screen while their brain waves were monitored. Random chirping sounds were introduced to divert their attention from the screen.

The results of the study showed that when the DBS was inactive, Parkinson's patients, like the control group, diverted their attention from the visual to the auditory system in response to the chirping sound. However, when the DBS was activated, the patients with Parkinson's did not shift their visual attention. This finding suggests that the subthalamic nucleus plays a crucial role not only in motor functions but also in thought and attention management.

Wessel emphasizes that deep brain stimulation should continue to be used for Parkinson's patients due to its positive effects on motor control. However, he and his team believe that further research is needed to fine-tune the technique and minimize potential side effects on attention and impulse control.

The study, titled "The human subthalamic nucleus transiently inhibits active attentional processes," was published in the journal Brain on March 4, 2021. The research was funded by the National Institutes of Health and the National Science Foundation.

This study provides valuable insights into the impact of deep brain stimulation in Parkinson's patients, highlighting the potential trade-offs between motor control improvement and cognitive functions related to attention and impulse control. Understanding these effects will contribute to the development of personalized treatments for Parkinson's disease, optimizing patient outcomes and overall quality of life.