- New research has found a link between loss of smell and the later development of Alzheimer’s.
- This association was observed in people who possess a particular gene variant called APOE e4.
- Experts say loss of smell can be used to predict future cognitive problems.
- Certain lifestyle choices can help lower your risk of Alzheimer’s.
- There are also medications that can slow its progression.
A new study published in the medical journal Neurology report that those individuals who carry the APOE e4 gene variant—which is associated with an increased risk of Alzheimer’s disease (AD)—may lose their sense of smell only as they develop the disease.
The authors note that identifying odors requires both the ability to recognize and name odors and the ability to detect their presence (olfactory sensitivity).
Carriers of this particular allele tend to lose smell sensitivity long before they experience loss in smell recognition, they wrote.
The loss of smell sensitivity also occurs well before reductions in cognitive abilities.
According to the authors, this early loss of smell could be considered a harbinger of future thinking and memory problems.
For the study, 865 people completed a survey that tested both their ability to detect an odor and whether they could name what the odor was. They were tested every five years.
They also completed tests of their thinking and memory on two occasions, five years apart.
DNA testing was used to identify who carried the gene variant that increases the risk of Alzheimer’s disease.
Participants were scored on a scale of zero to six based on what concentration of an odor was needed for them to detect it.
The research team found that people with the APOE e4 allele were 37% less likely to be good at detecting the smell than those without the variant.
This was after excluding other factors such as age, gender and education.
Reductions in odor detection began to be observed at ages 65 to 69.
Changes in people’s ability to identify what the smell was didn’t show up until ages 75 to 79.
But when they lost their ability to name odors, this ability declined faster compared to those who did not have the Alzheimer’s gene variant.
Those with the gene variant also experienced faster loss of cognitive skills over time.
Dr. Leah Alexandera board-certified pediatrician in New Jersey who was not part of the study said, “This may be due to the fact that olfactory neurons (or those that detect odors) are among the most vulnerable to damage from beta-amyloid, one of the proteins associated with Alzheimer’s disease.”
Alexander went on to say that this study highlights how important it is to consider both environmental and genetic factors in the risk of developing Alzheimer’s disease.
She further noted that these findings suggest that a decline in a person’s sense of smell may provide an early warning sign that allows people to take steps to prevent further decline through lifestyle changes and other measures.
Dr. Alejandro Alvathe founder, chief medical officer and CEO of Pacific Neuropsychiatric Specialists (PNS), who was also not involved in the study, said: “Apart from age, there are other risk factors that may contribute to an increasing number of individuals developing Alzheimer’s disease.
These risk factors include having a sedentary lifestyle, obesity, smoking, overeating, high blood pressure and more.”
However, Alva said there are certain lifestyle changes that can reduce your risk as well as improve your overall health. He suggests the following:
- Manage high blood pressure. Alva advises you to take medication prescribed by your doctor, eat a range of heart-healthy foods and manage your salt intake by consuming less than 5g daily.
- Maintain regular physical activity. Participating in aerobic exercise for 150 minutes per week helps reduce risk, especially when combined with other healthy lifestyle factors.
- Avoid binge drinking. “Drinking alcohol can increase the loss of brain cells and can induce the accumulation of toxic protein in the brain,” he explained. “It is advised to drink in moderation or stop the habit altogether.”
- Stop smoking. “The chemicals and toxins from cigarettes can cause inflammation and stress on brain cells that can significantly increase the risk of Alzheimer’s disease,” Alva said.
Alexander added that there are medications available that have been shown to delay the onset of Alzheimer’s disease or slow its progression.
Alzheimer’s Association lists aducanumab (Aduhelm) and lecanemab (Leqembi) as two FDA-approved drugs currently used to manage the disease.
Finally, Alexander emphasized that it is important to be aware that Alzheimer’s disease is a complex condition and that there is no single thing you can do to guarantee that you will not develop it.
“However, by taking preventive measures and understanding one’s risk factors, individuals may be able to reduce their chances of developing this degenerative disorder,” she concluded.
New research has found a link between loss of smell and the later development of Alzheimer’s. This association was observed in people who possess a particular gene variant called APOE e4.
Experts say loss of smell can be used to predict future cognitive problems.
Certain lifestyle choices can help lower your risk of Alzheimer’s. There are also medications that can slow its progression.