Gender Matters: Nonlinear Relationships Between Heart Rate Variability and Depression and Positive Affect

Abstract

Vagally mediated heart rate variability (vmHRV), a measure of the parasympathetic nervous system's control over the heart, is often negatively related to maladaptive emotional outcomes. Recent work suggests that quadratic relationships involving these factors may be present; however, research has not investigated gender differences in these nonlinear functions. To address this gap, the current study tested for quadratic relationships between resting vmHRV and depression and positive affect while investigating gender differences in these relationships. Significant quadratic effects were found between resting vmHRV and reports of both depression symptoms and positive affect in women but not men. Specifically, the lowest levels of depression and the highest levels of positive affect were found at moderate vmHRV in women. These results suggest that examinations of vmHRV's nonlinear associations require the consideration of gender. Our findings are interpreted based on proposed differential neuropsychological mechanisms of vmHRV in men versus women.

Keywords: autonomic nervous system; depression; emotion; gender; gender differences; heart rate variability; nonlinear; positive affect.

FIGURE 1

First row: Linear and quadratic effects of resting lnRMSSD on DASS-Depression scores in (A) men and (B) women separately. Second row: Linear and quadratic effects of resting lnRMSSD on PANAS-positive affect scores in (C) men and (D) women separately. LnRMSSD = natural log of root mean square of successive differences (in the natural log of millisecond units). LnRMSSD is grand-mean centered; DASS = depression anxiety stress scale. DASS-Depression scores are in inverse normalized units to reduce skew for parametric analyses. All results were identical (p < 0.05, one-tailed) when analyzing raw DASS-Depression scores. Significant (p < 0.05, one-tailed) quadratic effects were only detected in women, as depicted in (B,D).