Respiratory sinus arrhythmia and diseases of aging: obesity, diabetes mellitus, and hypertension.

Associations between respiratory sinus arrhythmia (RSA) and several chronic diseases, including obesity, diabetes mellitus, and hypertension, have been documented in recent years. Although most evidence suggests reduced RSA is the result of chronic disease rather than the cause, some studies have documented reduced RSA among at-risk individuals prior to disease onset. These results raise the possibility that decreased vagal tone may play a role in the pathogenesis of certain chronic diseases. Presented here is a brief overview of studies which examine the relationship between vagal tone, as measured by RSA and baroreflex gain, and diseases of aging, including obesity, diabetes mellitus, and hypertension. Mechanisms by which vagal tone may be related to disease processes are discussed. In addition, we present results from a population-based study of RSA and hypertension in older adults. Consistent with previous studies, we found an inverse relationship between RSA and age, cigarette use, and diabetes. In logistic regression models which control for age, cigarette use, and diabetes, we found RSA was a significant negative predictor of hypertension. We conclude that the relationship between RSA and hypertension is somewhat independent of the age-related decline in parasympathetic activity.