In a small proof-of-concept study, measuring changes in 24-hour heart rate indicated with ~90% accuracy whether an individual suffered from depression. Future longitudinal studies with larger sample sizes are needed to further to gain more insight in heart rate as marker for antidepressant treatment approaches.
Dr Carmen Schiweck (Goethe University, Frankfurt) explained: “An innovative study design with the rapid-acting antidepressant ketamine was designed to assess the potential of heart rate or heart rate variability as state marker for depression. We aimed to assess the potential of real-life psychophysiological measures as state markers for depression” . Two innovative elements in this study were the continuous registration of heart rate for several days and nights, as well as the new antidepressant ketamine, which has a fast onset of action. The average resting heart rate may change quite suddenly to reflect the change in mood.
A small sample of patients with major depressive disorder who did not respond to normal treatment (n=16) and healthy controls (n=16) were included in the study. Heart rates were measured for 4 days and 3 nights, after which patients were treated with either ketamine or placebo.
Patients suffering from depression had a higher baseline heart rate (P<0.001; approx. 10-15 beats higher) and a lower heart rate variation compared with healthy controls. After treatment with ketamine, both heart rate and heart rate fluctuation of the patients had changed and become more similar to the controls. Interestingly, the 24-hour heart rate appeared to be an accurate biomarker for depression. Patients were fitted with a wearable mini-ECG that fed the data to an artificial intelligence programme. This programme was able to classify almost 90% of controls and patients correctly as being depressed or not. Dr Schiweck elaborated: “Normally, heart rates are higher during the day and lower during the night. Interestingly, it seems that the drop in heart rate during the night is impaired in depression. This seems to be a way of identifying patients who are at risk to develop depression or to relapse.”
Moreover, patients with a higher resting heart rate responded better to the treatment with ketamine. However, the study was a small proof-of-concept study, and larger studies are needed to further evaluate the role of heart rate as a biomarker for depression.
- Schiweck C, et al. Heart rate and heart rate variability as trait or state marker for depression? Insights from a ketamine treatment paradigm. P.257. ECNP Congress 2020.
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