The confusion in diagnosing bipolar depression and the inadvertent medication induced manic switch can be largely avoided henceforth. Thanks to the work of physicians at Loyola medicine, distinguishing between major depressive disorder and bipolar depression could be as simple as getting an ECG done!
This will prevent misdiagnoses that could trigger a manic episode due to the prescription of an antidepressant without a safeguard mood stabilizer.
591 adults with major depression and 116 adults with bipolar disorder underwent electrocardiograms. Data for 15 minutes were collected and heart rate variability was studied using software programs.
Heart rate variability – heart rate variability (HRV) measures the specific changes in time (or variability) between successive heart beats.
Patients with bipolar depression exhibited significantly lower mean R–R intervals, variance, low-frequency variance, and high-frequency variance but higher LF/HF ratio compared to those with unipolar depression.
Low-frequency HR variability – The low-frequency component of the heart rate variability spectrum (0.06–0.10 Hz) is often used as an accurate reflection of sympathetic activity.
High-frequency HR variability – 0.15 to 0.4 Hz- mediated by both the vagus and cardiac sympathetic nerves and reflects cardiac parasympathetic modulation rather than parasympathetic ‘tone’
Compared to the controls, the patients with bipolar depression showed cardiac sympathetic excitation with reciprocal vagal impairment, whereas the unipolar depression patients showed only vagal impairment.
This difference in vagal impairment and sympathetic tone is said to influence heart rate variability.
In the near future, we may have a working lab investigation to differentiate unipolar depression from bipolar depression.
References – Loyola University Health System “Simple EKG Can Determine Whether Patient Has Depression or Bipolar Disorder.”