title: The effect of Parkinson's disease subgroups on verbal and nonverbal fluency.
abstract: BACKGROUND
  Parkinson's disease (PD) leads to deficits in executive function, including verbal and nonverbal fluency, as a result of compromised frontostriatal circuits. It is unknown whether deficits in verbal and nonverbal fluency in PD are driven by certain subgroups of patients, or how strategy use may facilitate performance.
  
  
  METHODS
  Sixty-five nondemented individuals with PD, including 36 with right-body onset (RPD; 20 with tremor as their initial symptom, 16 nontremor) and 29 with left-body onset (LPD; 14 with tremor as their initial symptom, 15 nontremor), and 52 normal control participants (NC) took part in the study.
  
  
  METHODS
  Verbal fluency was assessed using the FAS and Animals tests. Nonverbal fluency was assessed using the Ruff Figural Fluency Test.
  
  
  RESULTS
  Both RPD and LPD were impaired in generating words and in using clustering and switching strategies on phonemic verbal fluency, whereas different patterns of impairment were found on nonverbal fluency depending on the interaction of side of onset and initial motor symptom (tremor vs. nontremor). Strategy use correlated with number of correct responses on verbal fluency in LPD, RPD, and NC. By contrast, on nonverbal fluency, strategy use correlated with correct responses for RPD and LPD, but not for NC.
  
  
  CONCLUSIONS
  Our findings demonstrate the importance of considering subgroups in PD and analyzing subcomponents of verbal and nonverbal fluency (correct responses, errors, and strategies), which may depend differently on the integrity of dorsolateral prefrontal cortex, inferior frontal cortex, and anterior cingulate cortex.
authors.affiliation: a Department of Psychological and Brain Sciences , Boston University , Boston , MA , USA.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Jaywant
authors.forename: Giovanni
authors.initials: G
authors.lastname: Musto
authors.forename: Sandy
authors.initials: S
authors.lastname: Neargarder
authors.forename: Karina
authors.initials: K
authors.lastname: Stavitsky Gilbert
authors.forename: Alice
authors.initials: A
authors.lastname: Cronin-Golomb
mesh_terms: D000368:Aged; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000523:psychology; D013064:Speech Disorders / Q000175:diagnosis* / Q000209:etiology*; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D014705:Verbal Behavior / Q000502:physiology*