Bidirectional brain-heart interactions in health and disease.

The brain and heart constantly communicate with each other to adapt to changes in the environment. In recent years, we have seen increasing recognition that brain-heart interactions influence many cognitive and behavioural functions, and that disturbances in this bidirectional relationship can have detrimental effects on both organs. Clinically, such disturbances can manifest as cardiac dysfunction following acute psychological stress or a brain injury such as acute ischaemic stroke, or as cognitive disorders in patients with acute or chronic heart disease. In this Review, we provide an overview of the physiological interaction between the heart and the brain and show how injury or dysfunction in one of these organs can lead to dysfunction in the other. We describe the current state of knowledge on neuronal correlates and humoral mediators of brain-heart interactions, as well as state-of-the-art methods for studying these interactions. We highlight the clinical implications of disturbances in physiological brain-heart communication for various clinical conditions, including Takotsubo syndrome resulting from emotional stress or from brain disorders, cardiac complications after stroke (so-called stroke-heart syndrome), and cognitive dysfunction in patients with cardiac diseases such as heart failure and atrial fibrillation. In addition, we address sex and gender differences in this bidirectional relationship.