Spirituality and autonomic cardiac control

Abstract

Background: Spirituality has been suggested to be associated with positive health, but potential biological mediators have not been well characterized.

Purpose and methods: The present study examined, in a population-based sample of middle-aged and older adults, the potential relationship between spirituality and patterns of cardiac autonomic control, which may have health significance. Measures of parasympathetic (high-frequency heart rate variability) and sympathetic (pre-ejection period) cardiac control were obtained from a representative sample of 229 participants. Participants completed questionnaires to assess spirituality (closeness to and satisfactory relationship with God). Personality, demographic, anthropometric, health behavior, and health status information was also obtained. A series of hierarchical regression models was used to examine the relations between spirituality, the autonomic measures, and two derived indexes--cardiac autonomic balance (CAB, reflecting parasympathetic to sympathetic balance) and cardiac autonomic regulation (CAR, reflecting total autonomic control).

Results: Spirituality, net of demographics, or other variables were found to be associated with enhanced parasympathetic as well as sympathetic cardiac control (yielding a higher CAR) but was not associated with CAB. Although the number of cases was small (N = 11), both spirituality and CAR were significant negative predictors of the prior occurrence of a myocardial infarction.

Conclusions: In a population-based sample, spirituality appears to be associated with a specific pattern of CAR, characterized by a high level of cardiac autonomic control, irrespective of the relative contribution of the two autonomic branches. This pattern of autonomic control may have health significance.

Figure 1

Cardiac Autonomic Regulation (CAR), as a function of age (median split) and gender. Overall, females show higher CAR scores than men, and these decrease for both genders with age.

Figure 2

Distribution of the high frequency heart rate variability (HF) and for pre-ejection period (PEP) acreoss age (median split) and gender. HF is in units of msec² (natural log of the integral spectral power in the respiratory frequency band), and PEP is in units of msec. Females have generally higher HF values (reflecting paraympathetic cardiac control) than males, and these values tended to decrease with age. Females also had lower PEP values (indexing sympathetic cardiac control) than men, and these values also tended to decrease with age.

Figure 3

Path analysis of mediation. Spirituality (AS) was significantly predictive of both cardiac autonomic regulation (CAR) and prior myocardial infarction. CAR was also predictive of myocardial infarction and may be a mediator of the relationship between spirituality and infarction, as spirituality was no longer predictive of myocardial infarction (c’) after the effects of CAR were accounted for. Values in parenthesis are the coefficients.