Did you know that a reduced sense of smell in a person may be linked to an increased risk of dementia? To ensure the health of our brain, just like a flower, the brain needs the nourishment of information flow, as well as the health of blood vessels and the immune system. To provide good information flow to the brain, there are many receiving organs, including our eyes, ears, mouth, and sense of smell. Like newborns who gradually build their own brain thinking by touching, putting things in their mouth, and smelling things, the loss of smell has been linked to the accumulation of pathological substances related to Alzheimer's disease in brain scans.

A recent study published in the Journal of Alzheimer's Disease examined 364 participants from Baltimore who were followed up for 2.5 years. During this process, real-time cognitive function tests, olfactory tests, and brain PET CT scans were performed on them. After 2.5 years, some of the more than 300 elderly people developed mild cognitive impairment, the prodromal stage of Alzheimer's disease, and some directly developed Alzheimer's disease. The authors analyzed the relationship between the baseline data and the development of dementia in the future. The study concluded that if a person's sense of smell is impaired, it is related to a 22% increase in the risk of mild cognitive impairment in the future. The results of this study were adjusted for a series of confounding factors, such as age, gender, race, and education. The researchers also found that lower olfactory scores were associated with certain brain areas related to smell in the brain, and the accumulation of pathological substances in Alzheimer's disease was related to a certain extent. Therefore, the researchers put forward a conjecture that the decreased sense of smell may be an early sign of the pathological appearance of Alzheimer's disease.

There is some evidence to suggest that improving the sense of smell may reduce the risk of dementia. For example, the more teeth lost, the higher the risk of dementia, but after installing dentures, the risk decreases. Similarly, the risk of dementia decreases after installing hearing aids for hearing loss.

However, there are relatively few studies on correcting the sense of smell. After the COVID-19 pandemic in 2019, about 20% of people lost their sense of smell, and more researchers are exploring how to strengthen it. Some researchers believe that some nerves related to taste and smell have a degree of elasticity. That is to say, if they are often stimulated, it can promote their recovery. Therefore, some proposed methods include using things with a stimulating aroma, such as clove, lemon eucalyptus oil, and rose flower oil, and smelling them for ten to 15 seconds twice a day for several weeks or months. However, the effectiveness of these methods still needs to be scientifically verified.