Age-related differences in prefrontal control of heart rate in humans: a pharmacological blockade study.

The Neurovisceral Integration Model is based on the premise of significant central nervous system-peripheral nervous system interactions. In support of this model we have previously shown that the prefrontal cortex tonically inhibits cardioacceleratory circuits as evidenced by increased heart rate (HR) when the prefrontal cortex is inactivated by injections of sodium amobarbitol (ISA) into the internal carotid artery. In this report we re-examine these data to investigate possible age-related differences in the prefrontal control of HR in humans. Seventy-three patients were divided into three groups based on a tertile split with mean ages of 20, 34, and 47, respectively. There were significant age-related differences in cortical control of HR as evidenced by a significant three way interaction of age (young, middle, old) by side (left versus right) by time (baseline and epochs 1-10 of inactivation) [Roy's Root (10,59)=0.378, p=0.028]. Results showed significant HR increases that did not differ between hemispheres in the youngest age group, significant increases in the middle age group that were larger in the right hemisphere than in the left, and significant HR increases in the oldest group in the right hemisphere only. The findings suggest important age-related differences in cortical inhibitory control of HR that appear less lateralized in the youngest group and significantly attenuated in the oldest age group. These results have important implications for the understanding of age-related differences in cognitive, affective, behavioral, and physiological functioning. In addition they support the importance of investigating central nervous system-peripheral nervous system relationships.