Effect of aging on cardiovascular responses to cold stress in humans

Cold exposure increases the risk of adverse events related to cardiovascular causes, especially in the elderly. In this review, we focus on recent findings concerning the impact of aging on the regulatory mechanisms of cold-induced cardiovascular responses. In response to cold exposure, the initial physiological thermoregulation in healthy young persons, such as cutaneous vasoconstriction to reduce heat loss, is attenuated in older individuals, resulting in a reduced ability of the older persons to maintain body temperature in cold environment. Impaired sympathetic skin response, reduced noradrenergic neurotransmitter synthesis, insufficient noradrenergic transmitters, and altered downstream signaling pathways inside the vascular smooth muscle may be among the underlying mechanisms for the maladaptive vasoconstrictive response to cold stress in the elderly. The increase in blood pressure during cold exposure in young persons may be further augmented in aging adults, due to greater central arterial stiffness or diminished baroreflex sensitivity with aging. Cold stress raises myocardial oxygen demand caused by increased afterload in both young and old adults. The elderly cannot adjust to meet the increased oxygen demand due to reduced left ventricular compliance and coronary blood flow with advancing age, rendering the elderly more susceptible to hypothermia-induced cardiovascular complications from cold-related diseases. These age-associated thermoregulatory impairments may further worsen patients' health risk with existing cardiovascular diseases such as hypertension, coronary artery disease, and heart failure. We searched PubMed for papers related to cold stress and its relationship with aging, and selected the most relevant publications for discussion.