Eye color and hypertension

Abstract

We searched for predictors of essential hypertension in 1,031 persons aged 30-49 who were observed to progress from normotension to hypertension, as compared to an equal number of matched subjects who remained normotensive. Blood pressure status was well documented in both multiphasic screenings and clinical records. Compared to persons with each lighter eye color, those with brown eyes were more prone to develop hypertension, with relative risk of 1.5 (95% confidence interval 1.18-1.96) compared to all persons with nonbrown eyes. The association persisted after control for race, sex, body mass index, alcohol use, educational level, parental history of hypertension, and among whites, for ethnic origin as crudely estimated by last name. Partial confirmation was obtained in three largely independent study groups: 1) 25 pairs of eye-color-discordant dizygotic twins; 2) 894 pairs of incident hypertensives and controls selected only with multiphasic screening blood pressure measurements; and 3) cross-sectional analysis of 152,018 multiphasic screenees. The weak association of eye color with hypertension clearly requires further confirmation. Although it has little potential for use in screening or clinical care, it may have implications regarding etiology. Areas for further exploration include the close metabolic relation of melanins to catecholamines, both derived from the amino acid tyrosine, and the possibility that dark-eyed persons react more quickly and strongly to stimuli than light-eyed persons.