The scientists studied 50 pairs of male twins between the ages of 47 and 57 who were free of symptomatic CHD. Twenty-four hour ambulatory electrocardiograms (ECGs) of these research subjects were analyzed and depressive symptoms were measured with the Beck Depression Inventory. The lifetime history of major depression of each man was also assessed with the Structured Clinical Interview for Psychiatry Disorders .
"Within each pair of twins we studied, HRV parameters were strongly related with the severity of depressive symptoms. A lifetime history of major depression was related to HRV only in presence of current depressive symptoms -- but people with depressive symptoms had decreased HRV also in absence of a lifetime history of major depression. These findings are important because decreased HRV is a heart disease risk factor," says Emory Heart Center cardiologist Viola Vaccarino MD, Ph.D., lead author of the study. "And these results are even more remarkable for the fact that they are derived from twin study design, which is semi-experimental and allows tight control for extraneous factors. "
She explains that HRV reflects the beat-to-beat fluctuations in heart rate noted on the EKG that are governed by the autonomic nervous system ( the portion of the nervous system that controls the body's visceral functions, including action of the heart). "Autonomic dysfunction, as reflected by decreased HRV, is a plausible mechanism linking depression
Contact: Sherry Baker
Emory University Health Sciences Center