A recent study found something intriguing: when mice with Alzheimer’s disease inhale menthol, their cognitive abilities improve.
It seems the chemical compound can mitigate some of the damage done to the brain that’s typically associated with the disease.
In particular, researchers noticed a reduction in the interleukin-1-beta (IL-1β) protein, which helps to regulate the body’s inflammatory response. This response can offer natural protection but leads to harm when it’s uncontrolled.
The team behind the study, published in April 2023, says it shows the potential for certain smells to be used as therapies for Alzheimer’s. If we can understand which odors produce specific brain and immune system responses, we might harness them to improve health.
“We have focused on the olfactory system’s role in the immune and central nervous systems, and we have confirmed that menthol is an immunostimulatory odor in animal models,” said immunologist Juan José Lasarte from the Center for Applied Medical Research (CIMA) in Spain when the results were released.
“Surprisingly, we observed that short exposures to this substance for six months prevented cognitive decline in the mice with Alzheimer’s and, what is most interesting, also improved the cognitive ability of healthy young mice.”
For mice with Alzheimer’s, a six-month regimen of menthol was sufficient to prevent the deterioration of cognitive abilities and memory. Additionally, it appears that menthol restored the IL-1β protein to safe levels in the brain.
Researchers found that artificially reducing the number of T regulatory (Treg) cells – which help regulate the immune system – led to similar effects, suggesting a potential pathway for future treatments.
“Both menthol exposure and Treg cell blockade caused a decrease in IL-1β, a protein linked to cognitive decline in these models,” said neuroscientist Ana Garcia-Osta from CIMA.
“Moreover, the specific blockade of this protein using a drug commonly prescribed for some autoimmune diseases also improved cognitive capacity in both healthy mice and those with Alzheimer’s.”
Scientists have identified numerous connections between smells and our immune and nervous systems. While these relationships are complex, it’s clear that our olfactory system significantly influences the brain. Certain smells can trigger brain responses that lead to chemical reactions affecting memory, emotion, and more.
“This study is an important step toward understanding the connection between the immune system, the central nervous system, and smell,” said immunologist Noelia Casares from CIMA.
The research has been published in Frontiers in Immunology.