Changes and persistence in heart rate variability before and during social stress: A comparison of individuals with and without social anxiety disorder.

Individuals with social anxiety disorder (SAD) experience significant and persistent fear of social situations as they anticipate rejection, scrutiny, and embarrassment. Given that physiological reactions to social situations may shape emotional experience in SAD, understanding psychophysiological changes operating in SAD may be important to address this potentially key perpetuating factor. This study compared the patterns of change (via contrasts of estimated marginal means) and persistence (via autoregressive models) of two indices of heart rate variability (HRV; Root Mean Square of Successive Differences between normal heartbeats, and High-Frequency absolute units) as physiological measures of emotion regulation, between individuals with SAD (n = 94) and without (n = 59) using the Trier Social Stress Test phases (TSST). Results revealed that the SAD group increased their need to regulate their emotions (peak HRV) during the preparation (i.e., anticipation) phase, particularly among women, whereas HRV peaked for the non-SAD group during the social-evaluative context. The SAD group's increase in HRV in the preparation phase, relative to non-SAD group, was the opposite of the hypothesised effect. The non-SAD group demonstrated no significant persistence of HRV between some TSST phases, whereas the SAD group showed significant persistence across all phases, however no between-group differences were found. These findings provide novel evidence of similarities and differences in HRV between individuals with and without SAD while anticipating and encountering social-evaluative contexts.