Changes in cognitive abilities after deep brain stimulation for Parkinson disease

Persons with Parkinson disease (PD) who have difficulties from side effects or dosing of medications, or both, have the option of undergoing deep brain stimulation (DBS). DBS provides electrical stimulation via electrodes implanted into one or both sides of the brain. These electrodes are connected to a programmable (adjustable) pulse generator (like a pacemaker) placed under the skin of the chest. The 2 most common targets for the brain electrodes are the subthalamic nuclei (STN) or globi pallidi (GPi). One of each of these targets is found in the left and right halves of the brain. These brain structures contain circuits important for motor functions or movement. Nearby in the brain are circuits that regulate emotion, mood, and cognition. Cognition refers to mental abilities such as memory, abstract thinking, and word finding. There is concern that the benefits of DBS for movement might be offset by negative effects of DBS on thinking and emotion. Studies have shown that DBS is safe from cognitive and emotional standpoints. Still, a minority of patients have problems with cognition and emotion after DBS. It is unclear whether stimulating the STN or GPi is safer. A few studies examining a small number of patients (and often using a limited number of tests) suggest that stimulation of the GPi might be safer than the STN for cognition and emotion.¹ A large well-done study is needed to help physicians and patients make the best choices. This study by Odekerken and colleagues² is 1 of 2 recently published that seek to address the important question of whether STN or GPi DBS is safer.