Effect of cold exposure on older humans.

Epidemiological studies have shown excess winter mortality particularly in older age groups. A question is how much these statistics are affected by age-related physiological changes in cold thermoregulation and how much due to other factors related to aging. In experimental studies concerning age and cold stress both whole-body and local exposures have been used mostly in resting subjects with minimal clothing. Older persons, particularly men over ca. 60 years, are less able to maintain core temperature during a given cold challenge compared to younger individuals. Older persons have a reduced cutaneous thermal sensitivity, and a reduced subjective thermal perception during cooling. Thus, older people may require a more intense stimulus to perform protective actions against cold stress. Older persons' skin vasoconstrictive response to cold is diminished compared to younger persons, which seems partly related to a reduced skin vasomotor sensitivity to sympathoneuronal stimuli. The cold-induced rise in metabolic rate is attenuated in older persons, but the mechanism is unknown. Both central and peripheral components seem to be involved in the age-related changes in regulatory effector functions. Enhanced aerobic fitness may not give added protection against core cooling during cold stress in the elderly, but seems to attenuate older subjects' heightened blood pressure response to cold. Bronchial responsiveness to face cooling may increase with age. Further studies are needed to examine the age-related changes in non-thermoregulatory responses to cold (e. g. hemodynamics, cardiac function, respiration, autonomic nervous function), and the modifying effects of acute exercise and physical training.