title: Cognition following bilateral deep brain stimulation surgery of the subthalamic nucleus for Parkinson's disease.
abstract: OBJECTIVE
  Parkinson's disease (PD) is a neurodegenerative disorder characterized by significant motor dysfunction and various non-motor disturbances, including cognitive alterations. Deep brain stimulation (DBS) is an increasingly utilized therapeutic option for patients with PD that yields remarkable success in alleviating disabling motor symptoms. DBS has additionally been associated with changes in cognition, yet the evidence is not consistent across studies. The following review sought to provide a clearer understanding of the various cognitive sequelae of bilateral subthalamic nucleus (STN) DBS while taking into account corresponding neuroanatomy and potential confounding variables.
  
  
  METHODS
  A literature search was performed using the following inclusion criteria: (1) at least five subjects followed for a mean of at least 3 months after surgery; (2) pre- and postoperative cognitive data using at least one standardized measure; (3) adequate report of study results using means and standard deviations.
  
  
  RESULTS
  Two recent meta-analyses found mild post-operative impairments in verbal learning and executive function in patients who underwent DBS surgery. However, studies have revealed improved working memory and psychomotor speed in the 'on' vs 'off' stimulation state. A deficit in language may be a consequence of the surgical procedure.
  
  
  CONCLUSIONS
  While cognitive decline has been observed in some domains, our review of the data suggests that STN DBS is a worthwhile and safe method to treat PD.
authors.affiliation: Department of Neurosurgery, Neurology and Psychiatry, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Casey H
authors.initials: CH
authors.lastname: Halpern
authors.forename: Jacqueline H
authors.initials: JH
authors.lastname: Rick
authors.forename: Shabbar F
authors.initials: SF
authors.lastname: Danish
authors.forename: Murray
authors.initials: M
authors.lastname: Grossman
authors.forename: Gordon H
authors.initials: GH
authors.lastname: Baltuch
mesh_terms: D000367:Age Factors; D000368:Aged; D001288:Attention; D001479:Basal Ganglia / Q000503:physiopathology; D003072:Cognition Disorders / Q000209:etiology* / Q000503:physiopathology; D046690:Deep Brain Stimulation / Q000009:adverse effects* / Q000379:methods; D056344:Executive Function; D006801:Humans; D007806:Language Disorders / Q000209:etiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D018579:Patient Selection; D011597:Psychomotor Performance; D013028:Space Perception; D020531:Subthalamic Nucleus / Q000503:physiopathology*; D016896:Treatment Outcome; D014706:Verbal Learning