Menthol and Cognitive Ability
Researchers from Cima University of Navarra in Spain have found that inhaling menthol can improve cognitive ability in animal models of Alzheimer’s disease.
The study revealed that repeated short exposures to menthol modulated the immune system and prevented the cognitive deterioration characteristic of this neurodegenerative disease.
Mechanism of Action
The team discovered that when the animals inhaled the menthol aroma, the level of interleukin-1-beta (IL-1b), a protein critical for mediating inflammatory response, was reduced.
By inhibiting IL-1b using a drug approved for certain autoimmune diseases, they also managed to improve cognitive ability in these mice.
Implications for Future Therapies
The findings highlight the therapeutic potential of odors and immune modulators.
They open the door to developing therapies that stimulate and train the olfactory system to prevent or alleviate the effects of Alzheimer’s and other central nervous system diseases.
The Brain, Smell, and Immune System
The brain’s functional balance depends on complex interactions between nerve cells, immune cells, and neural stem cells.
Previous studies have explored the immunomodulatory and neurological effects of odorants and found a correlation between the loss of smell and the onset of Alzheimer’s symptoms.
“We have confirmed that menthol is an immunostimulatory odor in animal models,” said Dr. Juan José Lasarte, director of the Immunology and Immunotherapy Program at Cima and principal author of the investigation.
Short exposures to menthol prevented cognitive decline in Alzheimer’s mice and improved the cognitive ability of healthy young mice.
Role of T Regulatory Cells
Blocking T regulatory cells, immune cells with immunosuppressive activity, also improved cognitive ability in Alzheimer’s mice and healthy young mice.
Both menthol exposure and Treg cell blockade reduced IL-1b levels, which could be the culprit behind the cognitive decline observed in these models.
Blocking this protein with a drug used to treat some autoimmune diseases also improved the cognitive abilities of healthy mice and those with Alzheimer’s disease, the researchers found.
“This study is an important step toward understanding the connection between the immune system, the central nervous system, and smell,” said Dr. Noelia Casares, a researcher at the Immunology and Immunotherapy Program and first author of the article.
The results of the study were published in the journal Frontiers in Immunology.
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