Researchers continue to search for a definitive solution to combat Alzheimer’s disease and other forms of dementia, acknowledging that no magical shield exists. However, encouraging evidence suggests a potential way to improve cognitive function and cut Alzheimer’s Dementia risk.

The prevalence of Alzheimer’s disease among Americans is rapidly increasing. Currently, there are over 6 million Americans of all ages living with Alzheimer’s.

In 2023, it is estimated that approximately 6.7 million Americans aged 65 and older have Alzheimer’s, with 73 percent of them being 75 years or older. This means that around 1 in 9 people aged 65 and above (10.7 percent) suffer from this condition. Additionally, nearly two-thirds of individuals with Alzheimer’s in the United States are women.

Comparatively, older Black Americans are approximately twice as likely as older Whites to have Alzheimer’s or other types of dementia. Similarly, older Hispanics are about one and a half times more likely than older Whites to have Alzheimer’s or other dementia-related conditions.

As the population of Americans aged 65 and older continues to grow, the number and proportion of individuals with Alzheimer’s or other dementias will also increase. It is projected that by 2050, the number of people aged 65 and older with Alzheimer’s may reach 12.7 million unless there are significant medical advancements to prevent or cure the disease.

Recently, the Alzheimer’s drug Leqembi received full approval from the Food and Drug Administration (FDA). This approval is significant as it is the first drug designed to slow the progression of the disease to receive complete regulatory clearance. Previous approved drugs solely targeted the symptoms of Alzheimer’s.

In a phase 3 clinical trial involving 1,795 patients with mild cognitive impairment or early-stage Alzheimer’s disease, the progression of the illness was slowed by 27% over an 18-month period with the use of Leqembi. However, it’s important to note that patients still experience decline while on the drug, albeit at a slower rate.

During the trial, approximately 12.6% of patients who received Leqembi developed brain swelling, compared to 1.7% of those in the placebo group. Brain bleeds were experienced by about 17% of the Leqembi group, compared to 9% in the placebo group. Similar side effects have been observed with another Alzheimer’s drug called Aduhelm, developed by Biogen, which also targets amyloid in the brain.

Three deaths in the clinical trials were also linked to the use of Leqembi.

Furthermore, the drug comes with a yearly list price of $26,500.

At least, cheaper than Aduhelm that cost $56,000 a year.

Considering alternative methods to enhance cognitive function and reduce the risk of dementia, the use of dietary supplements is prevalent among older adults, with an estimated 80 percent relying on them. However, research on the effectiveness of such supplements, including Vitamin D, in preventing or treating Alzheimer’s and other forms of dementia has yielded discouraging results, showing minimal or very low odds of success.

A recent study published in Frontiers in Immunology uncovered an intriguing finding. When mice with Alzheimer’s were exposed to menthol, their cognitive capabilities were enhanced, suggesting that this compound could potentially mitigate some of the typical brain damage associated with Alzheimer’s.

Menthol is a naturally occurring organic compound derived from peppermint and various mint plant varieties.

A study conducted by researchers at Cima University of Navarra in Spain revealed that inhaling menthol could enhance cognitive performance in animal models of Alzheimer’s disease. The study demonstrated that short, intermittent exposures to menthol have the potential to regulate the immune response and mitigate the cognitive decline associated with this type of neurodegenerative disease.

Upon investigating the underlying mechanism, the research team observed that the scent of menthol reduced the concentration of interleukin-1-beta (IL-1β), a protein crucial to the inflammatory response. Interestingly, when a drug designed to inhibit this protein, which is currently approved for treating certain autoimmune conditions, was used, it also resulted in improved cognitive function in the affected mice.

These findings highlight the potential therapeutic role of odors and immune modulators. They also pave the way for innovative therapies, including those involving olfactory system stimulation and exercise, to mitigate or prevent the effects of Alzheimer’s and other central nervous system disorders.

The results of this study were recently published in Frontiers in Immunology.

The brain’s functional balance relies on intricate interactions among various nerve cells, immune cells, and neural stem cells. Within this complex network, numerous investigations have focused on the influence of odors on immunological and neurological processes. Previous studies have also established a connection between diminished olfactory senses and the onset of Alzheimer’s disease symptoms.

Dr. Juan José Lasarte, the principal author of the study, explains that they have specifically examined the role of the olfactory system in the immune and central nervous systems and confirmed that menthol is an odor that stimulates the immune system in animal models.

Surprisingly, they discovered that “short exposures to this substance for six months prevented cognitive decline in mice with Alzheimer’s and, most interestingly, also improved the cognitive ability of healthy young mice.”

A noteworthy finding from the research team is that inhibiting the action of T regulatory cells, which are immunosuppressive immune cells, resulted in improved cognitive abilities in mice with Alzheimer’s disease. Furthermore, it led to noticeable benefits in the cognitive capacities of healthy young mice, as stated by co-author Dr. Ana García-Osta.

Both menthol exposure and the inhibition of T regulatory cells led to a reduction in IL-1β levels, a protein potentially responsible for the cognitive decline observed in these models. Significantly, when this protein was specifically blocked using a medication used for certain autoimmune diseases, there was an enhancement in the cognitive abilities of both healthy mice and those affected by Alzheimer’s.

This research represents a significant advancement in understanding the connection between the immune system, the central nervous system, and the sense of smell. The findings suggest that odors and immune modulators could play a critical role in the prevention and treatment of Alzheimer’s and other disorders related to the central nervous system.

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