Deep brain stimulation parameters associated with neuropsychological changes in subthalamic nucleus stimulation for refractory Parkinson's disease.

Background/aims: Parkinson's disease (PD) is an idiopathic progressive neurological disorder. Improvement in motor function of PD patients has been established with subthalamic nucleus (STN) deep brain stimulation (DBS). While variations in DBS settings (i.e. amplitude, frequency and pulse width) on motor function have been explored, little data has evaluated the relationship of DBS settings on cognitive function. This study evaluated the extent to which DBS settings were associated with cognitive function.

Methods: The study was a prospective clinical trial of STN DBS for the treatment of refractory PD. Twenty patients were evaluated once preoperatively and an average of 5 months following bilateral STN DBS. Measures included a test of motor disability, a neuropsychological test battery and subjective mood measures of anxiety and depression.

Results: Motor function significantly improved following bilateral STN DBS. Compared to preoperative performance, verbal fluency declined while visuoconstructional skills improved. Amplitude and pulse width were significantly correlated with measures of cognitive function. Multiple regression found DBS stimulator settings, along with anxiety, to be significant predictors of cognitive measures.

Conclusion: Increased amplitude and pulse width and decreased anxiety were associated with improved cognitive test scores. Although preliminary, these data have potential theoretical and clinical applications.