Mapping the Brain-Heart Connection Using Brain Lesions

Principal Investigator: Michael D. Fox

Authors: Kyuree Kim*, Frederic L.W.V.J. Schaper*, Martin A. Samuels, Michael D. Fox Affiliations: Center for Brain Circuit Therapeutics, Departments of Neurology, Psychiatry and Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA *These authors contributed equally
Lay Abstract

Patients with brain lesions, especially postmenopausal women, are at increased risk of heart disease following brain damage. However, it is unknown what brain regions or brain networks are causally involved in this process. In this study, we use causal information from patients with brain lesions and a wiring diagram of the human brain to identify a brain-heart network. This network extended previous findings of brain imaging of the brain-heart connection and identified a key hub for the heart’s representation in the brain. This brain-heart network may be used to identify patients at high risk for heart disease following brain damage and may lead to improved counselling of patients and new preventive strategies.

Scientific Abstract

Introduction:
The brain-heart connection remains incompletely understood. While it is well known that damage to the insula is associated with a high risk of cardiac disease after a brain lesion, it is unknown why lesions outside the insula cause cardiac disease. In this study, we use brain lesions causing cardiac disease and test whether they map to a common brain network.

Methods:
We identified 19 published coordinates of different brain regions that, when damaged, cause new-onset cardiac arrhythmia after stroke. We computed the functional connections of each coordinate using normative human connectome data (n=1000). The key hub connected to all coordinates was identified. We then defined a brain-heart network, assessed its overlap with previous neuroimaging studies, and tested whether ischemic strokes causing cardiomyopathy (n=24) damaged this network more than control lesions (n=625).

Results:
All coordinates were functionally connected to a key hub in the right insula. A brain-heart network defined by connectivity to this hub included brain regions implicated in previous neuroimaging studies such as the operculum, anterior cingulate, and central amygdala. Lesions causing cardiomyopathy damaged this network more than control lesions (p=0.007).

Conclusion:
Brain lesions causing cardiac disease map to a common brain network functionally connected to the insula.

Clinical Implications
We identified a common brain network connected to brain lesions causing new-onset cardiac disease. This network increases our understanding of the brain-heart connection and may be relevant for identifying patients at high risk for cardiac disease after brain lesions.

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