Is reduced heart rate variability associated with functional somatic disorders? A cross-sectional population-based...

Area of Science:

• Autonomic Nervous System Research
• Psychophysiology
• Clinical Medicine

Background:

• Functional somatic disorders (FSD) are hypothesized to stem from sympathetic nervous system (SNS) overactivity, suggested by low heart rate variability (HRV).
• Previous studies on HRV and FSD are limited by small sample sizes, selection bias, and failure to account for FSD symptom overlap.
• This study investigates the association between HRV and various FSDs, considering the confounding effect of chronic stress.

Purpose of the Study:

• To examine the relationship between heart rate variability (HRV) and different functional somatic disorders (FSD).
• To determine if chronic stress confounds the association between HRV and FSD.
• To explore the role of sympathetic predominance in the pathophysiology of FSD.

Main Methods:

• A cross-sectional, general population-based study involving 6891 participants aged 18-72.
• FSDs (chronic fatigue, widespread pain, irritable bowel, bodily distress) were assessed using validated questionnaires and interviews.
• Heart rate variability (HRV) was measured using an 'E-motion' HR monitor, and chronic stress was assessed via Cohen's self-perceived stress scale. Logistic regression analyses were employed.

Main Results:

• Individuals with FSD exhibited slightly higher mean heart rate (HR) and lower HRV in time-domain parameters.
• Associations between FSD and HRV in frequency-domain parameters were inconsistent.
• Adjusting for chronic stress led to a slight attenuation of the observed associations between FSD and HRV.

Conclusions:

• The findings support the hypothesis of sympathetic predominance in individuals with FSD.
• Chronic stress does not entirely account for the observed association between sympathetic activity and FSD.
• Causality remains undetermined: it is unclear whether sympathetic predominance is a cause or a consequence of FSD.