AGING AND HUMAN COLD TOLERANCE

Hypothermia is widely considered to be a more serious threat for older than for younger persons because of older persons' impaired ability t o defend body temperature during cold exposure. Some epidemiological s tudies indicate that the incidence of death from hypothermia increases with age, but surveys of body temperature normally maintained by olde r persons while in their own homes do not indicate a large incidence o f hypothermia. More reliable comparisons of thermoregulatory responses to cold stress in younger and older subjects have been performed unde r controlled conditions in laboratory experiments. Generally, older me n appear less able than younger men to defend their core temperature d uring experimental cold exposures. Cold exposure may elicit a slightly smaller rise in metabolic heat production, and the cutaneous vasocons trictor response to cold may be less responsive in old than in young m en. These aging effects may, however, be limited to men. In a recent s tudy, older women appeared to defend core temperature during cold expo sure as well as, or better than, younger women. Preventable changes in body composition and physical fitness rather than aging per se may co ntribute to impaired thermoregulatory responses to cold observed in ol der workers.