Neuroimmune Communication
How the nervous system and immune system signal each other, from sickness behavior to the vagus nerve, with the human trial results so far and why stress-and-immunity claims need care.
Content last updated . This page has not been medically reviewed.
Established ideas
The immune system talks to the brain. A review in Nature Reviews Neuroscience explains that after a peripheral infection, innate immune cells release pro-inflammatory cytokines that act on the brain to cause "sickness behavior". [1] The same review proposes that when immune activation continues for a long time, as in some chronic illnesses, the signal to the brain may contribute to depressive symptoms in vulnerable people, and may help explain why depression is more common in people who are physically ill. [1] This is a proposed link between inflammation and mood, not a statement that inflammation causes depression in everyone.The brain talks to the immune system. A 2021 review describes bidirectional interaction between the nervous and immune systems and maps how the brain communicates with immune cells through hormonal, sympathetic, parasympathetic, sensory and meningeal lymphatic routes. [2] The same review presents its brain-region map as a partial, conceptual framework for forming hypotheses. [2]
The brain is not sealed off. A 2025 review says the old view that the central nervous system is isolated from the immune system is flawed. There is substantial neuroimmune communication at the borders around the brain, including recently discovered meningeal lymphatic vessels, and the system enables surveillance and protection while preventing damage to brain tissue. [3] See also neuroinflammation research.
Stress and immune measures in people
A meta-analysis of more than 300 articles on psychological stress and human immune parameters found that brief stressors (lasting minutes) were associated with potentially adaptive upregulation of some innate parameters, exam-type stressors tended to suppress cellular immunity while preserving humoral immunity, and chronic stressors were associated with suppression of both. [4] The authors noted that subjective reports of stress generally did not associate with immune change. [4]Caution: these were changes in laboratory immune parameters. The abstract does not report how often people got sick, so these findings do not show that stress management changes infection rates. Practical stress guidance lives at how to relieve stress and stress and everyday habits.
Using nerves as a treatment: vagus nerve stimulation
The "inflammatory reflex" is a proposed vagus-nerve circuit that limits cytokine production. Device trials have tested whether stimulating it helps rheumatoid arthritis (RA), an autoimmune joint disease.| Study | Design | Result |
|---|---|---|
| RESET-RA (2026) [5] | 242 people with RA who had not done well on biologic or targeted drugs; double-blind, sham-controlled, 3 months; vagus nerve-targeted system | ACR20 response 35.2% active vs 24.2% sham (P = 0.0209); related serious adverse events 1.6%, all around surgery and resolved |
| Auricular (ear) VNS trial (2023) [6] | 113 people with active RA; double-blind, sham-controlled, 12 weeks | ACR20 25.0% active vs 26.9% sham; the authors concluded it did not meaningfully improve disease activity |
ACR20 is a standard measure meaning at least a 20% improvement in RA criteria. These results show a promising but limited and mixed picture: one device approach met its primary endpoint with a modest placebo-controlled gap, and another approach using the ear did not. Results from one device and stimulation method do not carry over to others or to over-the-counter "vagus nerve" gadgets. Regulatory status for these devices was not verified for this page. For other brain-stimulation devices see psychiatric context and home-use claims for neuromodulation. Consumer vagus-nerve tools and "nervous system reset" products are not covered by these trials.
Frequently asked questions
What does neuroimmune mean?
It describes the two-way communication between the nervous system and the immune system. [2]
Can inflammation affect mood?
A review proposes that sustained immune activation can lead to depressive symptoms in vulnerable people. [1] It is a mechanism-level link and does not apply to everyone, and it is not a reason to self-treat low mood.
Does stress weaken immunity?
In a large meta-analysis, chronic stress was associated with suppression of several immune measures, but subjective stress reports usually did not track immune change. [4]
Does vagus nerve stimulation treat autoimmune disease?
Evidence is mixed. A sham-controlled trial of a vagus nerve-targeted system in RA met its primary endpoint modestly, while an ear-stimulation trial did not show a meaningful improvement. [5][6]
Are there safe at-home ways to stimulate the vagus nerve for immunity?
The trials above tested specific medical devices under clinical supervision. They do not support consumer gadgets or exercises sold for "immune balance". [5][6]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and how to read claims
When you see a "neuroimmune" claim, ask: was it tested in people, with what comparator, and was the outcome a symptom score or just a lab marker? The library explains those distinctions at mechanism vs demonstrated benefit.
Evidence labels: two-way brain-immune signaling is established biology; inflammation-to-depression is a promising but limited hypothesis; vagus nerve stimulation for RA is mixed.
References
- From inflammation to sickness and depression: when the immune system subjugates the brain. Nat Rev Neurosci 2008. Read 2026-10-22.
- Neuronal regulation of immunity: why, how and where? Nat Rev Immunol 2021. Read 2026-10-22.
- Redefining CNS immune privilege. Nat Rev Immunol 2025. Read 2026-10-22.
- Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry. Psychol Bull 2004. Read 2026-10-22.
- Vagus nerve-mediated neuroimmune modulation for rheumatoid arthritis: a pivotal randomized controlled trial. Nat Med 2026 (RESET-RA). Read 2026-10-22.
- A Randomized, Double-Blind, Sham-Controlled, Clinical Trial of Auricular Vagus Nerve Stimulation for the Treatment of Active Rheumatoid Arthritis. Arthritis Rheumatol 2023. Read 2026-10-22.