Losing sense of smell could be one of earliest signs of 'silent killer'

26 July 2023 , 20:01
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New finding was revealed in tests (Image: Getty Images/iStockphoto)
New finding was revealed in tests (Image: Getty Images/iStockphoto)

An inability to smell things may show someone has early dementia, research suggests.

It found older adults with an Alzheimer’s gene were 37% less likely to have a good sense of smell. Carriers of APOE e4, which increases the risk of the memory loss condition, began losing the sense at 65 to 69 years old.

On a zero to six scale, carriers could detect an average of 3.2 smells compared with 3.9 for those without the gene. By 75 to 79, carriers struggled to identify smells. Thinking skills in carriers also declined faster over time.

Dr Matthew GoodSmith, of the University of Chicago, US, said: “Testing a person’s ability to detect odours may be a useful way to predict problems.” About 900,000 Brits have dementia, which may rise to 1.6m by 2040.

But two new drugs appear to slow the progress of Alzheimer’s. The five-year study on 865 older adults is in the journal Neurology.

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Losing sense of smell could be one of earliest signs of 'silent killer'Older adults with an Alzheimer’s gene were 37% less likely to have a good sense of smell (stock image) (Getty Images)

However these breakthrough drugs coming through the development pipeline will require better tests to diagnose Alzheimer’s earlier - before brain damage has occurred.

The research team tested how well participants could pick up an odour, and their ability to identify what they were smelling.

Alongside that, DNA samples provided insight into who carried the gene linked with an increase risk of Alzheimer’s.

Every five years, the experts sent a survey to 865 participants to complete at home, measuring their ability to detect an odour and whether they could to clock what they were smelling.

Each test produced a grade between zero and six grade.

The participants’ thinking and memory skills were also tested twice, five years apart, for the study published in the journal Neurology.

Dr GoodSmith added: “While more research is needed to confirm these findings and determine what level of smell loss would predict future risk, these results could be promising, especially in studies aiming to identify people at risk for dementia early in the disease.

“Identifying the mechanisms underlying these relationships will help us understand the role of smell in neurodegeneration.”

Martin Bagot

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