Effect of aging on gender differences in neural control of heart rate

TLDR

The study aimed to determine how gender influences sympathetic and parasympathetic heart‑rate regulation and its evolution with aging in adults aged 40–79. HRV was assessed by frequency‑domain analysis of short‑term R‑R intervals in eight 5‑year age strata of 598 women and 472 men, after excluding cardiovascular comorbidities and applying log transformation to skewed measures. Women had higher HF up to age 49 and men higher LF% and LF/HF through age 59, but by age 60 the sexes converged; absolute HRV decreased with age while relative measures remained stable until about 60, indicating parasympathetic dominance in women and sympathetic dominance in men that fade after 50 and 60 respectively.

Abstract

To clarify the influence of gender on sympathetic and parasympathetic control of heart rate in middle-aged subjects and on the subsequent aging process, heart rate variability (HRV) was studied in normal populations of women ( n = 598) and men ( n = 472) ranging in age from 40 to 79 yr. These groups were divided into eight age strata at 5-yr intervals and were clinically diagnosed as having no hypertension, hypotension, diabetic neuropathy, or cardiac arrhythmia. Frequency-domain analysis of short-term, stationary R-R intervals was performed, which reveals very-low-frequency power (VLF; 0.003–0.04 Hz), low-frequency power (LF; 0.04–0.15 Hz), high-frequency power (HF; 0.15–0.40 Hz), the ratio of LF to HF (LF/HF), and LF and HF power in normalized units (LF% and HF%, respectively). The distribution of variance, VLF, LF, HF, and LF/HF exhibited acute skewness, which was adjusted by natural logarithmic transformation. Women had higher HF in the age strata from 40 to 49 yr, whereas men had higher LF% and LF/HF between 40 and 59 yr. No disparity in HRV measurements was found between the sexes in age strata ≥60 yr. Although absolute measurements of HRV (variance, VLF, LF, and HF) decreased linearly with age, no significant change in relative measurements (LF/HF, LF%, and HF%), especially in men, was detected until age 60 yr. We conclude that middle-aged women and men have a more dominant parasympathetic and sympathetic regulation of heart rate, respectively. The gender-related difference in parasympathetic regulation diminishes after age 50 yr, whereas a significant time delay for the disappearance of sympathetic dominance occurs in men.