Publication date: May 20, 2025

BackgroundCognitive impairment and dementia are common findings in patients with Parkinson’s disease (PD). However, the long-term effects of subthalamic deep brain stimulation (STN-DBS) on cognition remain unclear. ObjectiveWe report short- and long-term effects of STN-DBS on cognition in PD. MethodsWe analyzed neuropsychological data before STN-DBS surgery, 3-month post-surgery, 1-year post-surgery and in a long-term follow-up (8-15 years post-surgery) to examine the effects of STN-DBS on cognition. Results81 patients with a mean disease duration of 13. 0 years were examined before surgery. 50. 6% were identified with mild cognitive impairment (MCI), having a mean disease duration of 14. 2 years. Pre-surgical PD-MCI was not associated with clinically diagnosed dementia (PD-D) before death or before long-term follow-up (OR 0. 8, 95% CI 0. 3-2. 2, p = 0. 714), but disease duration at the time of surgery was associated with development of PD-D (OR 1. 2, 95% CI 1. 1-1. 3, p = 0. 005). Verbal fluency declined significantly 3 months after surgery, while other domains remained unaffected. In neuropsychological testing at long-term follow-up (N = 29), global cognitive impairment or dementia was found in 19 patients. The presence of depressive symptoms before surgery was associated to PD-D at long-term follow-up. Death before long-term follow-up was more common in patients with pre-surgical MCI than in patients with normal cognition. ConclusionsInfluence on cognition was described in a short- and long-term follow-up study up to 15 years after STN-DBS surgery in PD. Disease duration, but not pre-surgical MCI was associated with development of dementia. Impaired verbal fluency was observed both in a short- and long-term follow-up.

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