The association between heart rate variability and skin conductance: a correlation analysis in healthy individuals and patients with somatic symptom disorder comorbid with depression and anxiety

Objective To investigate the correlations between heart rate variability (HRV) and skin conductance (SC) in two populations under three different situations. Methods This cross-sectional study enrolled patients with somatic symptom disorder comorbid with depression and anxiety and healthy individuals without a psychiatric history. The biological signals were measured under three conditions: resting state, during a cognitive task and during paced breathing. Pearson's correlation analysis and the generalized estimating equation were used to examine the correlations between SC and HRV in the two populations under the three situations. Results The study enrolled 97 patients with somatic symptom disorder comorbid with depression and anxiety and 96 healthy individuals. In healthy individuals, the ratio of low-frequency power to high frequency power (LF/HF) and normalized LF (LF%) were significantly correlated with SC in the resting state and during a cognitive task, but the correlation coefficients were low level. In patients with somatic symptom disorder comorbid with depression and anxiety, LF/HF and LF% did not show significant correlations with SC under any situation. Conclusions The two different populations and three situations might have affected the significance of the LF/HF-SC and LF%-SC correlations. The generally low correlations indicate that LF/HF and LF% cannot fully reflect the sympathetic cholinergic activity represented by SC.

Automated summary

This study investigated the correlations between heart rate variability (HRV) and skin conductance (SC) in two populations under three different situations. The results showed significant correlations between HRV and SC in healthy individuals during the resting state and cognitive task, but not in patients with somatic symptom disorder comorbid with depression and anxiety. The findings suggest that HRV may not fully reflect the sympathetic cholinergic activity represented by SC.