Respiratory sinus arrhythmia reactivity in current and remitted major depressive disorder.

OBJECTIVE Low resting respiratory sinus arrhythmia (RSA) levels and blunted RSA reactivity are thought to index impaired emotion regulation capacity. Major depressive disorder (MDD) has been associated with aberrant RSA reactivity and recovery to a speech stressor task relative to healthy controls. Whether impaired RSA functioning reflects aspects of the depressed mood state or a stable vulnerability marker for depression is unknown. METHODS We compared resting RSA and RSA reactivity between adults with MDD (n = 49), remitted depression (RMD, n = 24), and healthy controls (n = 45). Electrocardiogram data were collected during a resting baseline, a paced-breathing baseline, and two reactivity tasks (speech stressor, cold exposure). RESULTS A group by time quadratic effect emerged (F(2,109) = 4.36, p = .015) for RSA across phases of the speech stressor (baseline, instruction, preparation, speech, recovery). Follow-up analyses revealed that those with MDD uniquely exhibited blunted RSA reactivity, whereas RMD and controls both exhibited the anticipated task-related vagal withdrawal and posttask recovery. The group by time interaction remained after covariation for age, sex, waist circumference, physical activity, and respiration, but not sleep quality. CONCLUSIONS These results provide new evidence that aberrant RSA reactivity marks features that track the depressed state, such as poor sleep, rather than a stable trait evident among asymptomatic persons.