Background: We investigated the cognitive and psychiatric outcome 6-months after bilateral subthalamic nucleus deep brain stimulation (DBS) for the treatment of Parkinson’s disease (PD) using a disease control group.
Methods: Twenty-three DBS patients were compared to 28 medically-treated PD patients at baseline and 6-months on neuropsychological measures. In addition to the group outcomes, we report reliable change indices (RCI) and a dementia caseness analysis.
Results: The DBS patients demonstrated a significant decline in verbal memory compared to the control group (p < 0.003), and trends for decline on oral information processing, including verbal fluency, timed transcription, and word naming. DBS patients demonstrated declines in attention, set shifting, and semantic fluency, however, these changes were similar to the PD groups’ rate of decline. RCI indicated that DBS patients demonstrated clinically significant declines in verbal fluency (p <0.01) and inhibition of a dominant response (p <0.003), with trends for declines in set shifting (p<0.02) and verbal long-term recall (p <0.08), indicative of frontostriatal dysfunction. DBS patients did not demonstrate significant changes in depression, anxiety, or psychological distress scores. The caseness analysis revealed that one of the DBS patients (4%) converted to dementia over 6-months compared to none of the PD controls.
Conclusions: Our findings demonstrate that DBS patients experience declines in verbal recall and trends for declines in oral information processing 6-months following surgery even when good motor outcome is achieved. Potential candidates should be counseled about the risk of mild frontostriatal cognitive declines following DBS to weigh the risks and benefits of the surgery.
- deep brain stimulation
- parkinson's disease