Researchers at the University of Göttingen have identified a potential biomarker that may predict how patients with major depressive disorder (MDD) respond to magnetic brain stimulation therapy. The study, published today in Brain Medicine, found that patients whose heart rate slows within the first 45 seconds of treatment show significant symptom improvement six weeks later.
“Early changes in cardiac rhythm could serve as valuable biomarkers for stratifying patients, allowing more personalized and effective treatment strategies,” said Roberto Goya-Maldonado, MD, clinician-scientist at the University Medical Center Göttingen.
MDD affects hundreds of millions worldwide and remains challenging to treat. About one-third of patients do not respond to standard antidepressant therapies. Magnetic brain stimulation, particularly repetitive transcranial magnetic stimulation (rTMS), has emerged as a promising alternative for treatment-resistant depression. This noninvasive technique stimulates underactive brain regions implicated in mood regulation.
In the current study, 75 patients received intermittent theta-burst stimulation (iTBS), a rapid form of rTMS that shortens session duration. Heart rates were continuously monitored via electrocardiogram during treatment.
Analysis revealed that patients with a marked heart rate deceleration within 45 seconds exhibited significantly greater clinical improvement after six weeks. Additionally, lower heart rate variability during the first 270 seconds correlated with symptom improvement after just one week.
A slower heart rate likely reflects activation of the frontal-vagal pathway, a neural circuit linking the prefrontal cortex to the heart via the brainstem, which is involved in mood regulation. Patients receiving sham treatment did not show this association, indicating that iTBS actively engages mood-regulating circuits when heart rate slows.
The study also explored personalized stimulation sites based on individual brain connectivity patterns, but this approach did not significantly impact long-term outcomes.
Current iTBS protocols achieve response rates of 30–50%. Incorporating heart rate monitoring could enable clinicians to adjust parameters such as coil positioning or stimulation intensity in real time, potentially improving outcomes. Heart rate monitoring is simple to implement and does not require expensive neuroimaging equipment.
If confirmed in larger trials, tracking heart rate during iTBS could allow physicians to rapidly identify responders, optimize treatment strategies, or pivot to alternative therapies, reducing the weeks-long delay often experienced before symptom improvement.
Related topics
