Autonomic Function May Have Directional Effect on Depression
Dysregulation of the autonomic nervous system is more likely to be a risk factor for depression rather than a sequela.
Depression and autonomic dysregulation are associated bidirectionally, though it is more likely that autonomic function affects risk for depression, according to a study recently published in JAMA Psychiatry.
This longitudinal study included 146 male participants. There were consistent correlations between heart rate variability in their first visit and Beck Depression Inventory-II (BDI-II) score in their second visit with the study researchers (β coefficients between -0.14 and -0.29), though neither antidepressant use nor baseline characteristics could explain these associations. Although a comparable association was evident in the other direction, in visit 1 BDI-II and visit 2 heart rate variability (β coefficients between 0.05 and -0.30), its presence could be accounted for by use of antidepressants. Dizygotic twins showed stronger associations between visit 1 heart rate variability and visit 2 BDI-II than monozygotic twins, though both showed significant associations.
The mean age of the participants was 54±3 years, and 138 were white. These participants were recruited using a twin registry. All had been in the US military during the time of the Vietnam War and had varying levels of depression. The study researchers performed baseline assessments between 2002 and 2006 and a follow-up 7 years later. They utilized BDI-II to assess symptoms of depression and used continuous electrocardiogram monitoring to measure heart rate variability. The direction of the association between heart rate variability and depressive symptoms was analyzed using β coefficients in multivariable mixed-effects regression models. Dizygotic and monozygotic twin associations were analyzed independently.
The study researchers conclude that “[the] association between depression and autonomic dysregulation, indexed by [heart rate variability], is bidirectional, with stronger evidence suggesting that autonomic function affects depression risk rather than vice versa…. These findings highlight an important role of autonomic nervous system in the risk of depression and contribute new understanding of the mechanisms underlying the comorbidity of depression and cardiovascular disease.”
Huang M, Shah A, Su S, et al. Association of depressive symptoms and heart rate variability in Vietnam War-era twins: a longitudinal twin difference study [published online May 16, 2018]. JAMA Psychiatry. doi: 10.1001/jamapsychiatry.2018.0747