Here’s an interesting set of findings: Researchers have discovered that long-term allergy exposure in mice causes measurable changes in the brain.
The observed effect was twofold: an increase in new neuron production in the hippocampus, which is responsible for memory; and a decrease in brain activity in the microglia, which regulates immune response:
“It was highly unexpected to see the deactivation of microglia in the hippocampus,” explained Barbara Klein, one of the authors of the study: “Partly because other studies have shown the reverse effect on microglia following bacterial infection.
“We know that the response of immune system in the body is different in case of an allergic reaction vs a bacterial infection. What this tells us is that the effect on the brain depends on type of immune reaction in the body.”
More study is of course needed to understand exactly why these responses occur, what effect they have on immune activity, and whether any of this is applicable to human beings. But it’s an interesting reminder that our brains respond to allergies in ways far more complex than a sneeze.