Affiliations: Unit of Functional Neurosurgery, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, The National Hospital for Neurology & Neurosurgery, London, UK
Correspondence:
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Correspondence to: Marjan Jahanshahi, BSc, MPhil, PhD, and Vishal Rawji, iBSc, MBPhD, Unit of Functional Neurosurgery, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, The National Hospital for Neurology & Neurosurgery, 33 Queen Square, London WC1N 3BG, UK. E-mail: m.jahanshahi@ucl.ac.uk. (Marjan Jahanshahi), E-mail: vishal.rawji.11@ucl.ac.uk. (Vishal Rawji)
Abstract: Background:Subthalamic nucleus deep brain stimulation (STN-DBS) successfully controls the motor symptoms of Parkinson’s disease (PD) but has associated cognitive side-effects. Objective:Establish the short- and long-term cognitive effects of STN-DBS in PD. Methods:Both the short-term and long-term effects of STN-DBS on cognition were examined through evaluation of the controlled studies that compared patients with STN-DBS to unoperated PD patients, thus controlling for illness progression. We also reviewed the literature to identify the factors that influence cognitive outcome of STN-DBS in PD. Results:The meta-analysis of the short-term cognitive effects of STN-DBS revealed moderate effect sizes for semantic and phonemic verbal fluency and small effect sizes for psychomotor speed and language, indicating greater decline in the STN-DBS operated than the unoperated patients in these cognitive domains. The longer-term STN-DBS results from controlled studies indicated rates of cognitive decline/dementia up to 32%; which are no different from the rates from the natural progression of PD. Greater executive dysfunction and poorer memory pre-operatively, older age, higher pre-operative doses of levodopa, and greater axial involvement are some of the factors associated with worse cognition after STN-DBS in PD. Conclusion:This evidence can be used to inform patients and their families about the short-term and long-term risks of cognitive decline following STN-DBS surgery and aid the team in selection of suitable candidates for surgery.
