reciprocal control, characteristic of

reciprocal control, characteristic of reflex processes, where autonomic balance can be biased toward one or the other of the autonomic branches. High scores indicate sympathetic dominance and low scores parasympathetic dominance. Independent estimates of sympathetic and parasympathetic control were obtained using standard measurement procedures, and the level of parasympathetic control was subtracted from sympathetic control to derive a measure of Cardiac Autonomic Balance. A second metric was designed to capture an alternative mode of autonomic control (Cardiac Autonomic Regulation) that assesses the degree of relative coactivation (rather than reciprocal activation) of both branches. This is a metric that taps into the non- reciprocal regulatory influences of higher neural structures. Cardiac Autonomic Regulation scores were derived by essentially summing activities of the sympathetic and parasympathetic branches to afford a measure of total overall autonomic cardiac control. High scores indicate high activation and low scores indicate low activation of both branches of the autonomic nervous system. In the 50-68-year-old adults in our sample, spirituality was found to be associated not only with a lower incidence of heart attack, but a higher level of Cardiac Autonomic Regulation. That is, people who felt closer in their relationship with God exhibited higher overall autonomic regulation—both sympathetic and parasympathetic. This was associated, in part, with lesser diminution of parasympathetic control and a greater degree of coactivation. Moreover, Cardiac Autonomic Regulation (but not Cardiac Autonomic Balance) predicted better overall health Page |55 status and was associated with a lower incidence of heart attack. Participants who had low Cardiac Autonomic Regulation were more likely to have suffered from a heart attack. Could higher Cardiac Autonomic Regulation scores explain why spirituality was associated with less risk for heart attack? That is, could a pattern of autonomic regulation associated with spirituality explain the link between spirituality and heart attack? In order to address this question, we conducted statistical tests of these linkages. As we already knew, both spirituality and Cardiac Autonomic Regulation are associated with a lower incidence of heart attack. When the predictive effects of spirituality were statistically extracted, Cardiac Autonomic Regulation continued to be a significant predictor of a lower incidence of heart attack. However, when the linkage test was reversed and the effects of Cardiac Autonomic Regulation were extracted, Spirituality was no longer a significant predictor. This indicates that Cardiac Autonomic Regulation is a plausible mediator that may explain the relationship between spirituality and heart attack. By capturing higher levels of parasympathetic control and the associated autonomic coactivation of the sympathetic and parasympathetic branches, Cardiac Autonomic Regulation provided a critical metric that permitted the study of a previously “invisible” and mysterious link between spirituality and health outcomes. This in no way diminishes the relationship between spirituality and health, but rather offers an important hypothesis as to how spirituality may impact physiology and health status. Spirituality reflects an important aspect of the HOUSE_OVERSIGHT_021301