Am J Psychiatry 1997; 154:694-696
Copyright © 1997 by American Psychiatric Association
Apolipoprotein E epsilon 4 allele and pupillary response to tropicamide
S Higuchi, S Matsushita, Y Hasegawa, T Muramatsu, H Arai and M Hayashida
Division of Clinical Research, National Institute on Alcoholism, Kurihama National Hospital, Kanagawa, Japan.
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. METHOD: 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.
