An investigation into the effects and prognostic factors of cognitive decline following subthalamic nucleus stimulation in patients with Parkinson's disease.

We retrospectively investigated the effects of subthalamic nucleus stimulation (STN-DBS) on new postoperative onset of cognitive decline and prognostic factors for advanced Parkinson's disease (PD). We studied 39 PD patients who had received bilateral STN-DBS. Clinical symptoms, cognitive function, psychiatric function, and health-related quality of life (HRQOL) were assessed before and six months after surgery. Based on the results of neuropsychological examinations six months after the surgery, the subjects were divided into those with and those without cognitive decline. We compared pre- and post-operative assessments between the two groups. Prognostic factors were investigated using multiple logistic regression analyses. Seven patients had cognitive decline six months after the operation (17.9%); they were significantly older than those without cognitive decline. Preoperative neuropsychological examinations revealed impairments in language and executive function. No differences were found in clinical symptoms. Patients with cognitive decline had significantly worse apathy scale scores. The HRQOL revealed significant declines in the Mental Component Summary (MCS), vitality, and mental health (MH) domains. Postoperative comparisons revealed novel significant differences in activities of daily living in the "on" and "off" states and in daytime drowsiness. Preoperative differences seen in the MCS and vitality indices were no longer present. Word fluency, and apathy scale and MH scores were independent preoperative prognostic factors for cognitive decline. New postoperative onset of cognitive decline due to STN-DBS affected activities of daily living and psychiatric function. Preoperative non-motor symptoms may be prognostic factors for new onset of cognitive decline.