title: Reduced Verbal Fluency following Subthalamic Deep Brain Stimulation: A Frontal-Related Cognitive Deficit?
abstract: OBJECTIVE
  The decrease in verbal fluency in patients with Parkinson's disease (PD) undergoing subthalamic nucleus deep brain stimulation (STN-DBS) is usually assumed to reflect a frontal lobe-related cognitive dysfunction, although evidence for this is lacking.
  
  
  METHODS
  To explore its underlying mechanisms, we combined neuropsychological, psychiatric and motor assessments with an examination of brain metabolism using F-18 fluorodeoxyglucose positron emission tomography, in 26 patients with PD, 3 months before and after surgery. We divided these patients into two groups, depending on whether or not they exhibited a postoperative deterioration in either phonemic (10 patients) or semantic (8 patients) fluency. We then compared the STN-DBS groups with and without verbal deterioration on changes in clinical measures and brain metabolism.
  
  
  RESULTS
  We did not find any neuropsychological change supporting the presence of an executive dysfunction in patients with a deficit in either phonemic or semantic fluency. Similarly, a comparison of patients with or without impaired fluency on brain metabolism failed to highlight any frontal areas involved in cognitive functions. However, greater changes in cognitive slowdown and apathy were observed in patients with a postoperative decrease in verbal fluency.
  
  
  CONCLUSIONS
  These results suggest that frontal lobe-related cognitive dysfunction could play only a minor role in the postoperative impairment of phonemic or semantic fluency, and that cognitive slowdown and apathy could have a more decisive influence. Furthermore, the phonemic and semantic impairments appeared to result from the disturbance of distinct mechanisms.
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Neurology, Rennes University Hospital, Rennes, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Houvenaghel
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Nuclear Medicine, Eugène Marquis Hospital, Rennes, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Le Jeune
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Dondaine
authors.affiliation: Department of Neuroradiology, Rennes University Hospital, Rennes, France.
authors.forename: Aurore
authors.initials: A
authors.lastname: Esquevin
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Psychiatry, Rennes University Hospital, Rennes, France.
authors.forename: Gabriel Hadrien
authors.initials: GH
authors.lastname: Robert
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; 'Neuroscience of Emotion and Affective Dynamics' laboratory, Department of Psychology, and Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland.
authors.forename: Julie
authors.initials: J
authors.lastname: Péron
authors.affiliation: Department of Neurosurgery, Rennes University Hospital, Rennes, France; "MediCIS" laboratory (UMR 1099 LTSI), Inserm/University of Rennes, Rennes, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Haegelen
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Neurology, Rennes University Hospital, Rennes, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Drapier
authors.affiliation: "MediCIS" laboratory (UMR 1099 LTSI), Inserm/University of Rennes, Rennes, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Jannin
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Psychiatry, Rennes University Hospital, Rennes, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Lozachmeur
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; 'Neuroscience of Emotion and Affective Dynamics' laboratory, Department of Psychology, and Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland.
authors.forename: Soizic
authors.initials: S
authors.lastname: Argaud
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France.
authors.forename: Joan
authors.initials: J
authors.lastname: Duprez
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Psychiatry, Rennes University Hospital, Rennes, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Drapier
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Neurology, Rennes University Hospital, Rennes, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Vérin
authors.affiliation: "Behaviour and Basal Ganglia" research unit (EA 4712), University of Rennes, Rennes, France; Department of Neurophysiology, Rennes University Hospital, Rennes, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Sauleau
mesh_terms: D000368:Aged; D003071:Cognition; D003072:Cognition Disorders / Q000503:physiopathology* / Q000523:psychology; D046690:Deep Brain Stimulation / Q000009:adverse effects*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology* / Q000523:psychology / Q000628:therapy; D012660:Semantics; D013060:Speech; D020531:Subthalamic Nucleus / Q000473:pathology*; D014825:Vocabulary