APOLIPOPROTEIN-E EPSILON-4 ALLELE AND PUPILLARY RESPONSE TO TROPICAMIDE

Objective: This study was designed to investigate in cognitively norma l subjects the possible association between hypersensitive pupil dilat ion responses to the cholinergic antagonist tropicamide and the presen ce of the apolipoprotein E epsilon 4 (APOE4) allele, a well-defined ge netic risk factor for Alzheimer's disease. Method: The authors measure d tropicamide-induced changes in pupil area in 44 cognitively normal J apanese subjects with and without the APOE4 allele. Results: The subje cts 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 hyp ersensitive pupil dilation response to tropicamide is already present in cognitively normal individuals with the APOE4 allele. This associat ion also suggests the potential involvement of APOE4 in the mechanism of pupil dilation.