Your heart is older than your brain. It beats, autonomously, 4 weeks after conception and does not stop until death. Moving at a glacial pace, the brain sparks to life 9 weeks later . The sagacious heart rests at the center of your chest, part of a dense endocrine and immune network that processes neurological signals. All independent from the brain. All to maintain the body in exquisite balance. Is it any surprise then, that disturbances in this delicate rhythm affect brain function?
In Ancient Greece, the widely held theory was that the heart acted as a brain - collecting information from all other organs through the circulatory system. Each transitory emotion, each perverse thought, catalogued by a bloody fist-sized pump. Outrageous. Or is it?
The brain and heart communicate through the vagus nerve, the lengthiest cable of the autonomic nervous system. 85-90% of fibers in the vagus nerve are devoted to transmitting cardiovascular signals to the brain. More than any other organ. Critical messages from the nervous, endocrine and immune systems are received through the coded language of neurotransmitters, hormones and cytokines.
In turn, mental processes exert considerable influence on endocrine and immune systems. To illustrate how emotion can trigger a fatal cascade, take anger. After that jerk cuts you off (without signaling, of course), your heart signals your brain to enter the flight-fight response, a hyperarousal state that results in the secretion of epinephrine (adrenaline). You get a boost of energy. You might tail him. You might honk. You might try to burn out his retinas with your high beams. Cortisol is secreted to dampen the immune system. No time for combating germs. You begin shaking, your face is flushed and your pupils are dilated . If left unchecked, these effects can lead to myocardial ischemia, arrhythmia and even sudden death. That’s right, road rage can kill you.
And women have it worse. Three times worse. First, the elevated heart rate: on average, 8 beats faster. Second, increased heart failure risk if depression is involved. And third, takostubo.
Japan 1990. A striking heart condition known as takostubo cardiomyopathy is first described. Named after an octopus trap, the temporary condition is defined as a weakening of the left ventricle, the heart’s main pumping chamber. The cause? Severe emotional or physical stress: A serious accident, a natural disaster, the loss of a loved one.
The precise cause isn't known, but experts think that surging stress hormones (for example, adrenaline) essentially "stun" the heart, triggering changes in heart muscle cells or coronary blood vessels (or both) that prevent the left ventricle from contracting effectively. Researchers suspect that older women are more vulnerable because of reduced levels of estrogen after menopause.
This neurovisceral integration model, where the information shared between the heart and the brain is coded by rhythmic patterns, may represent the basis of intuitive-emotional processes, awareness and feelings, and a rational, detached and “less egocentric” reasoning.
In fact, Dr. Rajesh Kumar and his team at the University of California, Los Angeles recently proved a definitive link between heart and mind.
The neural responses to the Valsalva maneuver were evaluated in 29 patients with heart failure and 35 control subjects using fMRI. Blowing against a closed upper airway (holding nose with closed mouth), the healthy patients showed appropriate increases in heart rate, which quickly returned to baseline after exhaling. Patients with heart failure however, showed a slower and gradual decline, due to delayed neural responses in the areas responsible for mediating autonomic regulation.
But that’s not all.
Patients with heart failure also showed compromised brain function in areas responsible for emotion regulation and cognition.
The ventral medial prefrontal, bilateral orbital frontal, cuneus and middle occipital cortices, all regions that regulate cognitive, executive, attentional and emotional functions showed tissue changes in patients with heart failure. These changes corresponded with cognitive and mood regulation issues, difficulty with complex reasoning and inability to absorb and retain information. There was also less activation in the insular cortices, indicating impaired interoceptive awareness of body states, further contributing to dysregulation of heart and blood pressure.
The Greeks were very nearly right. The heart does read the musical notes of each emotion. It then conducts the neuroendocrine-immune symphony to play back on the coronary endothelium using its exquisitely tuned instruments: hormones, neuropeptides, and cytokines.
I think we should all listen closely.
Dal Lin, Carlo, Tona, F., Osto, E. (2018). The heart as a psychoneuroendocrine and immunoregulatory organ. Springer Nature, pp. 225-239.
Song, X., Roy, B., Fonarow, G., Woo, M. and Kumar, R. (2018). Brain structural changes associated with aberrant functional responses to the Valsalva maneuver in heart failure. Journal of Neuroscience Research, 96(9), pp.1610-1622.