Alzheimer’s disease: Loss of smell may be the sign?

Alzheimer’s disease: Loss of smell may be the sign?

More than 6 million people in the United States are affected by Alzheimer’s disease, which is the most prevalent type of dementia.

The key to controlling the condition is early detection, yet first symptoms like memory problems are frequently written off as normal aging symptoms.

According to a recent study, those who contain the APOE4 gene mutation, who are more likely to acquire Alzheimer’s disease, may begin to lose their sense of smell sooner than people who do not.

Testing people’s sense of smell could assist identify those at higher risk of Alzheimer’s because this reduced sense of smell may be an early marker of future cognitive issues.

Around 1 in 9 Americans over the age of 65, or 6.7 million people, have Alzheimer’s disease (AD), according to the Alzheimer’s Association. By 2050, scientists predict that this number will surpass 12 million due to an ageing population.

Alzheimer’s is a degenerative, incurable disease, but it is not a natural part of becoming older. If a person begins to have memory issues or cognitive deficiencies, these should not be ignored as normal ageing symptoms because early diagnosis enables effective therapy.

Globally, 13.7% of the population carries the APOE4 gene variation, which raises the risk of Alzheimer’s disease. 40% of those who are diagnosed with the illness have this gene.

According to a recent study in Neurology, those who have this gene mutation may have a compromised sense of smell before they show any signs of Alzheimer’s disease, like moderate cognitive impairment.

The researchers propose that screening for odour sensitivity may be helpful for identifying those who are at risk.

Alterations in scent brought on by Alzheimer’s

In order to conduct the study, 865 participants responded to a survey that measured their capacity for odour detection as well as their ability to identify the odour. Every five years, they underwent testing.

Additionally, they conducted two tests of their memory and thinking, with a five-year gap between each test.

Who carried the gene mutation that enhanced risk for Alzheimer’s disease was determined by DNA testing. Based on the concentration of an odour that participants had to be exposed to in order to notice it, scores ranged from zero to six.

The study’s team discovered that those with the APOE e4 allele had a 37% lower likelihood of being adept at smelling things than those without it. This came after age, sex, and education were all taken into account.

Between the ages of 65 and 69, odour detection started to decline.

It wasn’t until participants reached the ages of 75 to 79 that changes in their capacity to detect the smell started to show. However, compared to people without the Alzheimer’s gene variation, once they lost the capacity to name smells, this skill deteriorated more quickly.

Those who had the gene mutation also aged more quickly in terms of cognitive decline.

Losing one’s sense of smell could be an early sign of Alzheimer’s.

Over the course of the trial, those who had the gene were 37% less likely than those who did not to have effective odour detection.

Age-related loss in odour sensitivity was observed in those with the APOE 4 variant at 65 years of age, as compared to those without the gene. However, non-carriers, who initially had a greater sense of smell, showed a faster drop beyond the age of 65.

At 65, there was no difference between carriers and non-carriers in their capacity to recognise odours, but this ability started to diminish more quickly in carriers, especially around age 75. Similar trends were seen in cognition, with those with the APOE 4 variation seeing quicker decreases in cognition.

Although the researchers did not discover a connection between odour detection and cognition, their data do imply a connection between odour identification and cognition.

The authors discovered that APOE 4 carriers had odour sensitivity impairments that manifested sooner in life (65–69 years old) than odour identification impairments (75–79 years old), according to Dr. Clark, who was not involved in the study. Additionally, among APOE 4 carriers, odour sensitivity deficiencies came before cognitive deterioration.

She continued, “This shows that reduced odour sensitivity may be an early indication of future cognitive impairment in APOE 4 carriers.”

How to lower your chance of getting Alzheimer’s?

In addition to not participating in the study, Dr. Alejandro Alva is the founder, chief medical officer, and CEO of Pacific Neuropsychiatric Specialists (PNS). He also stated that there are other risk factors besides age that can contribute to an increased number of people developing Alzheimer’s disease.

Sedentary behavior, obesity, smoking, excessive drinking, high blood pressure, and other things are among these risk factors.

However, according to Alva, there are several lifestyle modifications that can lower your risk and enhance your general health. He offers the following advice:

  • Control your blood pressure. Alva suggests following any medical advice, eating a range of heart-healthy foods, and keeping your salt intake under 5 g per day.
  • Continue your usual exercise regimen. 150 minutes per week of aerobic exercise helps reduce risk, especially when combined with other aspects of a healthy lifestyle.
  • Stop drinking excessively. “Drinking alcohol can increase the loss of brain cells and can induce the accumulation of toxic protein in the brain,” he said. “It is advised to drink in moderation or to completely kick the habit.”
  • Give up 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,” claimed Alva.

The development of Alzheimer’s disease can be delayed or slowed down with the use of certain drugs, Alexander continued.

Lecanemab (Leqembi) and aducanumab (Aduhelm) are two FDA-approved drugs that are being used to control the illness, according to the Alzheimer’s Association.

She added, “However, individuals may be able to lower their chances of acquiring this degenerative condition by adopting preventative actions and identifying one’s risk factors.


An association between the loss of scent and the later onset of Alzheimer’s has been discovered by recent research. People with a certain gene variant known as APOE e4 were the ones that showed this connection.

According to experts, the loss of smell may be utilized to anticipate future cognitive issues. Your risk of Alzheimer’s may be lowered by making certain lifestyle decisions. Additionally, several drugs might stop it in its tracks.


For Alzheimer’s disease medications that have been suggested by doctors worldwide are available here

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