- 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 could be used to predict future cognitive problems.
- Certain lifestyle choices may help decrease your risk for Alzheimer’s.
- There are also medications that may delay its progression.
A new study published in the medical journal Neurology reports that those individuals who carry the gene variant APOE e4 — which is linked with an increased risk for Alzheimer’s disease (AD) — may lose their sense of smell first 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 (odor sensitivity).
Carriers of this particular allele tend to lose odor sensitivity long before experiencing losses in odor recognition, they wrote.
The loss of odor sensitivity also occurs well before reductions in cognitive ability.
According to the authors, this early loss of olfactory ability 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, with five years elapsing in between the tests.
DNA testing was used to identify who carried the gene variant conferring increased risk for Alzheimer’s disease.
Participants were scored on a scale of zero to six based on what concentration of an odor was necessary for them to detect it.
The research team found that people carrying the APOE e4 allele were 37% less likely to be good at detecting the odor than those without the variant.
This was after ruling out other factors such as age, sex, and education.
Reductions in odor detection began to be observed between the ages of 65 to 69.
Changes in people’s ability to identify what the odor was did not appear until the ages of 75 to 79.
However, once they lost their ability to name odors, this ability declined faster when compared to those who did not possess the Alzheimer’s gene variant.
Those with the gene variant also saw quicker loss of cognitive skills over time.
Dr. Leah Alexander, a board certified pediatrician in New Jersey, who was not a 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.”
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Alexander went on to say that this study highlights just 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 could provide an early warning sign, allowing people to take steps to prevent further decline through lifestyle changes and other measures.
Dr. Alejandro Alva, the founder, chief medical officer, and CEO of Pacific Neuropsychiatric Specialists (PNS), who also did not take part in the study, said, “Aside from age, there are other risk factors that can contribute to an increasing number of individuals acquiring Alzheimer’s disease.
These risk factors involve having a sedentary lifestyle, obesity, smoking, binge drinking, having high blood pressure, and more.”
Alva said, however, 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 taking any medications prescribed by your doctor, eating a variety of heart-healthy foods, and managing your salt intake by consuming less than 5 g daily.
- Maintain regular physical activity. Engaging in aerobic exercise for 150 minutes a week helps lower risk, especially in conjunction 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 quit the habit entirely.”
- 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,” said Alva.
Alexander added that there are medications available that have been shown to delay the onset of Alzheimer’s disease or slow its progression.
Finally, Alexander stressed, it is important to be aware that Alzheimer’s disease is a complex condition and there is no single thing you can do to guarantee that you won’t develop it.
“However, by taking preventative 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 could be used to predict future cognitive problems.
Certain lifestyle choices may help decrease your risk for Alzheimer’s. There are also medications that may delay its progression.