title: Apolipoprotein E epsilon 4 allele and pupillary response to tropicamide.
abstract: OBJECTIVE
  This study was designed to investigate in cognitively normal subjects the possible association between hypersensitive pupil dilation response to the cholinergic antagonist tropicamide and the presence of the apolipoprotein E epsilon 4 (APOE4) allele, a well-defined genetic risk factor for Alzheimer's disease.
  
  
  METHODS
  The authors measured tropicamide-induced changes in pupil area in 44 cognitively normal Japanese subjects with and without the APOE4 allele.
  
  
  RESULTS
  The subjects with the APOE4 allele had significantly greater increases in pupil area than the others. The significant correlation of changes in pupil area with age for the subjects with the APOE4 allele was lacking for those without this allele.
  
  
  CONCLUSIONS
  The results suggest that a hypersensitive pupil dilation response to tropicamide is already present in cognitively normal individuals with the APOE4 allele. This association also suggests the potential involvement of APOE4 in the mechanism of pupil dilation.
authors.affiliation: Division of Clinical Research, National Institute on Alcoholism, Kurihama National Hospital, Kanagawa, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Higuchi
authors.forename: S
authors.initials: S
authors.lastname: Matsushita
authors.forename: Y
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: T
authors.initials: T
authors.lastname: Muramatsu
authors.forename: H
authors.initials: H
authors.lastname: Arai
authors.forename: M
authors.initials: M
authors.lastname: Hayashida
mesh_terms: D000375:Aging / Q000235:genetics; D000483:Alleles; D000544:Alzheimer Disease / Q000453:epidemiology / Q000235:genetics; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D015878:Mydriasis / Q000235:genetics; D011680:Pupil / Q000187:drug effects*; D014331:Tropicamide / Q000494:pharmacology*
chemical_list: D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D014331:Tropicamide