Measuring people’s sense of smell in later life could help doctors predict how likely they are to be alive in five years’ time, a PLOS One study suggests.
A survey of 3,000 adults found 39% with the poorest sense of smell were dead within five years – compared to just 10% who identified odours correctly. Scientists say the loss of smell sense does not cause death directly, but may be an early warning sign.
Researchers from the University of Chicago asked a representative sample of adults between the ages of 57-85 to take part in a quick smell test. The assessment involved identifying distinct odours encased on the tips of felt-tip pens.
The smells included peppermint, fish, orange, rose and leather.
Five years later some 39% of adults who had the lowest scores (4-5 errors) had passed away, compared with 19% with moderate smell loss and just 10% with a healthy sense of smell (0-1 errors).
And despite taking issues such as age, nutrition, smoking habits, poverty and overall health into account, researchers found those with the poorest sense of smell were still at greatest risk.
The odour of orange was considered harder to identify than the smell of peppermint
Exactly how smell loss contributes to lifespan remains unclear, but the researchers put forward a number of possible reasons behind the link. They say a reduced ability to sniff out odours could signal less regeneration or repair of cells in the body overall, as a healthy sense of smell depends partly on a continual turnover of cells that line the nose.
And a worsening sense of smell may serve as a mirror for a lifetime’s exposure to pollution and bugs, they say.
