Scientists discover one of the earliest signs of Alzheimer’s – and you might spot it at dinner time

LOSING your sense of smell early could indicate you’re more at risk of Alzheimer’s, a study shows.

The surprising symptom is more common in people who carry the gene making them susceptible to the disease, US researchers found.

People with the gene were 37 per cent less likely to have a good sense of smell in older age than those who did not.

Dr Matthew Goodsmith, of the University of Chicago, said: “Testing a person’s ability to detect odours may be a useful way to predict future problems with cognition.

“These results could be promising, especially in studies aiming to identify people at risk for dementia early in the disease.

“More research is needed to confirm these findings and determine what level of smell loss would predict future risk.”

Around 944,000 Brits are currently living with dementia and experts predict the numbers will exceed 1million by the end of the decade.

Alzheimer’s is the most common form of the condition, and is thought to be caused by build-ups of proteins in the brain, including tau and amyloid.

Memory loss is the most commonly-associated symptom of the disease, but it can also cause you to lose your appetite — or start eating too much.

People who carry the APOE-e4 gene are more likely to develop Alzheimer's, with experts estimating up to 65 per cent of people with the disease have the gene.

The study, published in Neurology, tested around 865 adults’ sense of smells every five years and compared it to their thinking and memory skills.

DNA samples also gave researchers information about who carried the gene associated with an increased risk of Alzheimer’s.

Researchers tested whether people could detect smells as well as tell apart which ones were caused by what, earning a score out of six for odour detection.

Those who carried the gene saw their senses of smell deteriorate from age 65 to 69.

At that age, the gene carriers could detect an average of about 3.2 of the smells, compared to about 3.9 smells for the people who did not carry the gene.

The people carrying the gene variant did not show a difference in their ability to identify what odour they were smelling until they reached age 75 to 79.

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