title: Progression in prediagnostic Huntington disease.
abstract: OBJECTIVE
  To examine rates of decline in individuals at risk for Huntington disease (HD).
  
  
  METHODS
  106 individuals at risk for HD completed a battery of neurocognitive, psychomotor and oculomotor tasks at two visits, approximately 2.5 years apart. Participants were classified as: (1) without the CAG expansion (normal controls, NC; n=68) or (2) with the CAG expansion (CAG+; n=38). The CAG+ group was further subdivided into those near to (near; n=19) or far from (far; n=19) their estimated age of onset. Longitudinal performance in the CAG+ group was evaluated with a repeated measures model with two main effects (time to onset, visit) and their interaction. Analysis of covariance was employed to detect differences in longitudinal performance in the three groups (NC, near and far).
  
  
  RESULTS
  In the CAG+, the interaction term was significant (p < or = 0.02) for four measures (movement time, alternate button tapping, variability of latency for a memory guided task and percentage of errors for a more complex memory guided task), suggesting the rate of decline was more rapid as subjects approached onset. Longitudinal progression in the three groups differed for several variables (p<0.05). In most, the near group had significantly faster progression than NC; however, comparisons of the NC and far groups were less consistent.
  
  
  CONCLUSIONS
  Different patterns of progression were observed during the prediagnostic period. For some measures, CAG+ subjects closer to estimated onset showed a more rapid decline while for other measures the CAG+ group had a constant rate of decline throughout the prediagnostic period that was more rapid than in NC.
authors.affiliation: Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202-5251, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Rupp
authors.forename: Tanya
authors.initials: T
authors.lastname: Blekher
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Jackson
authors.forename: Xabier
authors.initials: X
authors.lastname: Beristain
authors.forename: Jeanine
authors.initials: J
authors.lastname: Marshall
authors.forename: Siu
authors.initials: S
authors.lastname: Hui
authors.forename: Joanne
authors.initials: J
authors.lastname: Wojcieszek
authors.forename: Tatiana
authors.initials: T
authors.lastname: Foroud
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D018450:Disease Progression; D005260:Female; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000453:epidemiology / Q000235:genetics* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics; D009483:Neuropsychological Tests; D009687:Nuclear Proteins / Q000235:genetics; D011596:Psychomotor Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D012438:Saccades; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D019680:Trinucleotide Repeat Expansion / Q000235:genetics; D055815:Young Adult
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins