title: Non-Verbal and Verbal Fluency in Prodromal Huntington's Disease.
abstract: BACKGROUND
  This study examines non-verbal (design) and verbal (phonemic and semantic) fluency in prodromal Huntington's disease (HD). An accumulating body of research indicates subtle deficits in cognitive functioning among prodromal mutation carriers for HD.
  
  
  METHODS
  Performance was compared between 32 mutation carriers and 38 non-carriers in order to examine the magnitude of impairment across fluency tasks. The predicted years to onset (PYTO) in mutation carriers was calculated by a regression equation and used to divide the group according to whether onset was predicted as less than 12.75 years (HD+CLOSE; n = 16) or greater than 12.75 years (HD+DISTANT; n = 16).
  
  
  RESULTS
  The results indicate that both non-verbal and verbal fluency is sensitive to subtle impairment in prodromal HD. HD+CLOSE group produced fewer items in all assessed fluency tasks compared to non-carriers. HD+DISTANT produced fewer drawings than non-carriers in the non-verbal task. PYTO correlated significantly with all measures of non-verbal and verbal fluency.
  
  
  CONCLUSIONS
  The pattern of results indicates that subtle cognitive deficits exist in prodromal HD, and that less structured tasks with high executive demands are the most sensitive in detecting divergence from the normal range of functioning. These selective impairments can be attributed to the early involvement of frontostriatal circuitry and frontal lobes.
authors.affiliation: Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden; School of Medicine, University of Queensland, Brisbane, Qld., Australia.
authors.forename: Tarja-Brita
authors.initials: TB
authors.lastname: Robins Wahlin
authors.affiliation: School of Psychology, Flinders University, Adelaide, S.A., Australia.
authors.forename: Mary A
authors.initials: MA
authors.lastname: Luszcz
authors.affiliation: School of Health and Welfare, Jönköping University, Jönköping, Sweden.
authors.forename: Åke
authors.initials: Å
authors.lastname: Wahlin
authors.affiliation: School of Medicine, University of Queensland, Brisbane, Qld., Australia.
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Byrne
keywords: Cognition; Executive functioning; Neuropsychology; Non-verbal fluency; Phonemic fluency; Prodromal Huntington's disease; Semantic fluency