The Brain and the Immune System

The human brain is the seat of human function, the body’s control center, and the organ responsible for processing sensory information, coordinating actions, regulating automatic functions, and enabling cognition, language, and behavior. The brain is linked to movement, memory, emotions, and thoughts, as well as body temperature and involuntary processes like breathing and heart rate. Now, the link between the brain and the immune system is being more closely examined, as scientists explore whether focusing attention allows the brain to influence how the immune system responds to inflammation.

Constant Communication

Long thought to be separate and distinct from each other, the brain and the immune system are increasingly being perceived as connected.

“The two systems are constantly in communication,” said Jonathan Kipnis, a professor of pathology and immunology at Washington University in St. Louis who studies neuroimmune interactions. “The brain is involved in the individual’s survival, and the immune system is involved in survival, and that’s what they do. So of course they talk to each other.”

Controlling that conversation, and directing it to mitigate dysfunctional immune activity and inflammation, was the objective of researchers who directly tested whether voluntary attention could regulate acute inflammation in humans.

Attention, Please

Published in the journal Nature Human Behaviour, the study showed that – across three pre-registered within-subjects experiments using acute skin inflammation as a model system – directing attention towards bodily sensations, compared to attentional distraction, produced markedly more regulated immune responses, with distinct temporal dynamics.

Researchers induced acute cutaneous inflammation by administering histamine using the standardized prick test (SPT), while participants directed attention either internally to sensations of itching and burning at the test site or externally to distractors. In those who tried to distract themselves from the itch, the inflammation – as measured by redness and swelling of the skin – grew larger in size and lasted longer than in those who focused their attention on the site.

The authors noted that the effect was highly consistent, demonstrated in about 90% of participants across two independent cohorts, and substantial, with about 1.5-fold smaller responses under internal attention. Mechanistically, they added, two complementary pathways emerged: a sensory-dependent route, in which attentional modulation of the brain’s sensory processing system can either facilitate or inhibit its response based on attention, and a top-down route engaging parasympathetic activity of the vagus nerve, the tenth cranial nerve.

These results establish attention as a cognitive mechanism capable of regulating immune function in a living organism, according to the authors, and reframe perception as biologically consequential rather than merely experiential.

Cognitive Activity and Inflammatory Signaling

Cognitive activity and inflammatory signaling are deeply interconnected in a dynamic, bidirectional relationship, and their interaction may influence brain health as we age. Preserving mental engagement in aging may be as important as controlling vascular and metabolic risk factors in protecting the brain from inflammation-driven decline. Research in longevity science has explored whether maintaining cognitive activity may help preserve synaptic integrity and protect against age-related cognitive decline, while chronic inflammation can undermine the benefits of cognitive reserve and contribute to dementia risk.

Some of the factors being studied for their potential role in maintaining brain function as we age include:

The recent research connecting attention to immune function adds to growing evidence that the relationship between the brain and inflammation is more complex and potentially more modifiable than previously thought. However, whether these findings can translate into strategies for regulating neuroinflammation or improving brain health and healthspan remains an area for further research.

Concluding Thoughts

The concept that cognitive activity can interact with inflammatory signaling to create and control biological responses opens up a new perspective on brain health as we age. By studying how attention and other cognitive processes interact with the immune system, researchers may gain a better understanding of the brain’s role in regulating inflammation and the potential implications for health, healing, and longevity.

Sources:

Focusing Your Attention May Help Your Brain Fight Inflammation, Study Suggests 

Voluntary Attention Regulates Acute Immune Responses in Humans