Decreased vagal tone and higher levels of inflammatory biomarkers may differentiate bipolar disorder from major depressive disorder, suggesting utility of electrocardiogram to distinguish between the two disorders.
“Having a noninvasive, easy-to-use and affordable test to differentiate between major depression and bipolar disorder would be a major breakthrough in both psychiatric and primary care practices,” study researcher Angelos Halaris, MD, PhD, of Loyola University Medical Center, said in a press release.
To determine potential diagnostic criteria for major depressive disorder (MDD) and bipolar disorder, researchers quantified heart rate variability and inflammatory biomarkers among 64 individuals with MDD and 37 with bipolar disorder. Heart rate variability was assessed and blood taken prior to study initiation, at baseline and after antidepressant washout.
Participants with MDD had higher respiratory sinus arrhythmia (P = .05) and low frequency heart rate variability (P < .01) at baseline, compared with those with bipolar disorder.
Participants with bipolar disorder had significantly higher levels of interleukin 10 and monocyte chemoattractant protein-1 (MCP-1) at baseline, compared with those with depression.
Among participants with MDD, low frequency heart rate variability was positively associated with baseline interleukin 10 levels (P < .01).
“The present findings indicate that dysregulation of the [autonomic nervous system] and the immune system may underlie key pathophysiological differences between bipolar and unipolar depression,” the researchers wrote. “[Autonomic nervous system] activity assessment via [heart rate variability] measurements offers exciting possibilities for differential diagnostic evaluation and therapeutic management of depressive disorders.” – by Amanda Oldt
Disclosures: The authors reported no relevant financial disclosures.