As the body’s “command center,” the brain’s job is to communicate with other organs to make sure all our body systems are in proper working order. But you may not know that people who have brain injuries are also more likely to develop respiratory disorders. This is due to the brain-lung axis—how the brain and the lungs work (or, in some cases, don’t work) together. It is not an easy subject to study, given that there is not one, but two whole organs to analyze.

Maybe that’s why researchers across the globe are increasingly fascinated to figure out this brain-lung crosstalk, often described as a “double-hit” model. The brain and the lungs—equally important organs in their own respects—communicate through complex pathways that go in both directions:

Brain -> Lungs

Lungs -> Brain

Multiple studies have shown that respiratory failure and needing to go on mechanical ventilation are major risk factors for people who have neurological diseases. In fact, respiratory failure (not being able to breathe on your own) is one of the most severe and frequent organ dysfunctions that can happen outside of the brain in people with neurological impairment. Various studies suggest that changes in the blood-brain barrier that occur with brain injuries make pro-inflammatory cytokines unable to circulate around the body as well as they should. This affects other organs, such as the lungs. Pro-inflammatory cytokines are molecules that promote inflammation and are released by the immune system at the site of an injury.

Newer research has also shed light on the role of the hypothalamic-pituitary-gonadal (HPG) axis—the system in the brain that controls the release of sex hormones—in regulating disorders in other areas of the body, including the lungs. Scientists are exploring the crosstalk between the brains and lungs of people with asthma  to decipher the impact of psychological stress on asthma. My colleagues and I also have studied the role and function of kisspeptin, a neuropeptide hormone, in asthma.  

While researchers have developed strategies to protect the brain during traumatic injury, they fall short in maintaining lung health. The brain-lung axis relationship needs to be studied more definitively with a more translational approach in our understanding and implementing practices that consider how these organs work together and affect each other. Hopefully, in a few years from now, we can say confidently that we are not missing any puzzle pieces of how the brain and lungs talk to each other.