Emotional flexibility, thought to reflect the ability to adapt to internal and external environmental stimuli, is associated with psychological well-being. Emotional inertia and network density, defined as stability and interconnectedness, respectively, of emotions, are aspects of emotion dynamics that represent low emotional flexibility. Studies examining biological substrates of emotional persistence are largely limited to emotional inertia and non-depressed samples. Heart-rate variability (HRV) is a transdiagnostic biomarker for psychopathology thought to be associated with emotional flexibility. This study examined whether emotional inertia and network density were associated with HRV in adults with moderate-to-severe depression (N = 315). Participants completed three 8-day epochs of ecological momentary assessment (EMA) five times daily. Smartwatches measured HRV throughout the study. Emotional inertia and idiographic networks were calculated separately for EMA-rated negative and positive affect. Bayesian dynamic structural equation models with noninformative prior distributions examined the association between emotional inertia and HRV; hierarchical linear modeling examined associations between network density and HRV. Both daytime and bedrest HRV were inversely associated with temporal network density of negative emotions. HRV was not associated with inertia, positive network density, or average EMA-reported affect, though it was associated with age, antidepressant medication, and physical exercise. This was the first study to examine HRV in relation to these emotion dynamics in a depressed sample. The results suggest that experiencing a variety of negative emotions within a short period of time may be associated with underlying biological inflexibility. Future studies should examine the directionality and mechanisms behind this effect and explore potential clinical interventions.
Losiewicz et al. (Sun,) studied this question.