Cardiac Vagal Control in Non-Medicated Depressed Women and Non-Depressed Controls: Impact of Depression Status, Lifetime Trauma History and Respiratory Factors

Objective: Impairment in cardiac parasympathetic (vagal) control may confer risk for cardiac mortality in depressed populations. We evaluated the impact of acute stress and relationship-focused imagery on cardiac vagal control, as indicated by levels of respiratory sinus arrhythmia (RSA), in depressed and non-depressed women. Methods EKG and respiration rate were evaluated in 15 non-medicated depressed women and 15 matched controls during two laboratory conditions: (1) a relationship-focused imagery designed to elicit vagal activation, and (2) a speech stressor designed to evoke vagal withdrawal. Results As expected, the relationship-focused imagery increased RSA [F(3,66)=3.79, p=.02] and the speech stressor decreased RSA [F(3,66)=4.36, p=.02] across women. Depressed women exhibited lower RSA during the relationship-focused imagery, and this effect remained following control for respiratory rate and trauma history [F(1,21)=5.65, p=.027]. Depressed women with a trauma history exhibited the lowest RSA during the stress condition [F(1,22)=9.61, p=.05]. However, after controlling for respiratory rate, Trauma History × Task Order (p=.02) but not Trauma History × Depression Group (p=.12) accounted for RSA variation during the stress condition. Conclusion Depression in women is associated with lower RSA, particularly when women reflect on a close love relationship, a context expected to elicit vagal activation and hence increase RSA. In contrast, depression-related variation in stressor-evoked vagal activity appears to covary with women\u27s trauma history. Associations between vagal activity and depression are complex, and should be considered in view of the experimental conditions under which vagal control is assessed, as well as physiological and behavioral factors that may affect vagal function