title: Mild cognitive impairment in prediagnosed Huntington disease.
abstract: BACKGROUND
  Cognitive decline has been reported in Huntington disease (HD), as well as in the period before diagnosis of motor symptoms (i.e., pre-HD). However, the severity, frequency, and characterization of cognitive difficulties have not been well-described. Applying similar cutoffs to those used in mild cognitive impairment (MCI) research, the current study examined the rates of subtle cognitive dysfunction (e.g., dysfunction that does not meet criteria for dementia) in pre-HD.
  
  
  METHODS
  Using baseline data from 160 non-gene-expanded comparison participants, normative data were established for cognitive tests of episodic memory, processing speed, executive functioning, and visuospatial perception. Cutoff scores at 1.5 standard deviations below the mean of the comparison group were then applied to 575 gene-expanded pre-HD participants from the observational study, PREDICT-HD, who were stratified by motor signs and genetic risk for HD.
  
  
  RESULTS
  Nearly 40% of pre-HD individuals met criteria for MCI, and individuals closer to HD diagnosis had higher rates of MCI. Nonamnestic MCI was more common than amnestic MCI. Single-domain MCI was more common than multiple-domain MCI. Within the nonamnestic single-domain subtype, impairments in processing speed were most frequent.
  
  
  CONCLUSIONS
  Consistent with the Alzheimer disease literature, MCI as a prodromal period is a valid concept in pre-HD, with nearly 40% of individuals showing this level of impairment before diagnosis. Future studies should examine the utility of MCI as a marker of cognitive decline in pre-HD.
authors.affiliation: University of Utah, Salt Lake City, USA.
authors.forename: K
authors.initials: K
authors.lastname: Duff
authors.forename: J
authors.initials: J
authors.lastname: Paulsen
authors.forename: J
authors.initials: J
authors.lastname: Mills
authors.forename: L J
authors.initials: LJ
authors.lastname: Beglinger
authors.forename: D J
authors.initials: DJ
authors.lastname: Moser
authors.forename: M M
authors.initials: MM
authors.lastname: Smith
authors.forename: D
authors.initials: D
authors.lastname: Langbehn
authors.forename: J
authors.initials: J
authors.lastname: Stout
authors.forename: S
authors.initials: S
authors.lastname: Queller
authors.forename: D L
authors.initials: DL
authors.lastname: Harrington
mesh_terms: D000328:Adult; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis* / Q000235:genetics / Q000523:psychology*; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000150:complications / Q000175:diagnosis* / Q000235:genetics / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors