Sympathetic sudomotor function and aging

Many studies have reported the influence of aging on different portions of the autonomic nervous system components but only partially for the sympathetic cholinergic system. We evaluated postganglionic sudomotor function in 196 healthy subjects, 104 women and 92 men, by determining sweat gland density (SGD) per square centimeter of skin, on the dorsum of the hand and foot, with the impression mold technique. The age range was from 5 to 84 years. A significant decrease of SGD was observed in both hand and foot in relation to age (P < 0.001). The ANOVA analysis of foot data shows that age is the only significant factor for SGD reduction. In the hand, both sex and body surface area are significant covariates with age. The dorsum of the foot is the most appropriate place to examine sweating in studies of aging. The lower normal limits for SGD in the foot are 213/cm2 for subjects younger than 30 years, 199/cm2 for those from 30 to 59 years, and 123/cm2 for subjects over 59 years old.