Brain-heart interaction: an ECG-fMRI integrated study in physiology and major depressive disorder

Introduction. The connection between brain activity and cardiac variability, through the modulation of the autonomic nervous system, is a well-established phenomenon. However, the studies that have addressed the reciprocal influences between central and autonomic nervous system during resting state are still limited, especially in the context of pathophysiology. Aim. In the present work, the main objective was to explore the relationship between the central nervous system and cardiac variability at rest in an integrated multimodal analysis thanks to simultaneously acquired ECG and fMRI data. Moreover, we evaluated possible differences in adult-onset major depressive disorder (MDD), in which both brain function and cardiac variability alterations are evident, but in which there is still no idea of their reciprocal effects. Methods. Thirty-three participants were included in the study (67.33 ± 9.63 years, 58% females), 16 diagnosed with adult-onset MDD and 17 healthy controls (HC) with comparable age and sex. fMRI analysis was integrated with the analysis of the heart rate variability through an HRV-driven fMRI analysis to study the BOLD responses to sympathetic and vagal autonomic changes. Results. Our findings allowed to identify activations and deactivations in brain regions that are some of the key nodes of the central autonomic network (CAN), a network of brain structures that are involved in the regulation of autonomic processes at high central level. The comparison between patients affected by MDD and HC subjects revealed that differences in brain correlates of cardiac variability are present in brain regions of the CAN. Conclusions. Combined HRV-fMRI analyses provided new findings on physiological brain-heart interactions and allowed to characterize the autonomic and central neurobiological bases of depression from a wider and more comprehensive prospective.