Older people with a poor sense of smell are 50% more likely to die in the next 10 years, study finds – but scientists have no idea why
- Even healthy people at the beginning of the study had a higher death risk if their sense of smell was impaired
- It suggests the problem may flag up deteriorating health years before other problems
A poor sense of smell in retirement may be a warning sign of an early death, researchers have warned.
A study of more than 2,000 people in their 70s and early 80s found that those who had trouble recognizing common odors were almost 50 percent more likely to die in the next ten years than individuals with sensitive noses.
Even healthy people at the beginning of the study had a higher death risk if their sense of smell was impaired – suggesting the problem may flag up deteriorating health years before more serious problems appear.
Scientists believe smell tests could one day become routine in doctors’ surgeries.
Compared with those having a good smell sense, people in the ‘poor’ category were 46 percent more likely to die after 10 years and 30 percent after 13 years
Some experts even think a deteriorating sense of smell could be a red flag of the aging process – telling us more about the state of someone’s health than their age in numbers.
Researcher Dr Honglei Chen, from Michigan State University, said: ‘Poor sense of smell becomes more common as people age, and there’s a link to a higher risk for death.
‘Our study is the first to look at the potential reasons why it predicts a higher mortality.’
The team analyzed the sense of smell among 2,300 people aged between 71 and 82.
Each person was given 12 common odors to sniff, and for each smell were presented with four options from which to identify it from.
The participants were then classified as having a good, moderate or poor sense of smell depending on their accuracy – and then tracked for the next 13 years.
Compared with those having a good smell sense, people in the ‘poor’ category were 46 percent more likely to die after 10 years and 30 percent after 13 years.
The researchers, writing in the Annals of Internal Medicine journal, said poor sense of smell is already known to bee an early sign of Parkinson’s disease and dementia and is also linked to weight loss.
But they said this only explained 28 percent of the increased risk of death.
Dr Chen said: ‘We don’t have a reason for more than 70 percent of the increased risk. We need to find out what happened to these individuals.
‘It tells us that in older adults, impaired sense of smell has broader implications of health beyond what we have already known.
‘Incorporating a sense of smell screening in routine doctor visits might be a good idea at some point.’ Dr Chen said people who were worried about their sense of smell should talk to their GP.
‘It’s always prudent to talk to a physician about your health concerns,’ he said.
Professor Robert Howard, an expert in old age psychiatry at University College London, said: ‘The study showed that the risk of dying in the next 10 years was increased by about a half in people with impaired sense of smell and that only some of this risk could be explained by the development of Parkinson’s or Alzheimer’s or by weight loss.
‘Most of the increased mortality risk could not be explained by associations with specific illnesses such as cancer or cardiovascular disorders.
‘This raises the interesting possibility that loss of smell may be a marker of generalized aging and should be taken seriously by older people and their doctors.’ Professor Kevin McConway, an expert in applied statistics at the Open University, said the findings were ‘a real advance’.
But he added: ‘The trouble with any observational research like this is that it’s impossible to be sure about what’s causing what.
‘There are lots of differences between the people who could smell well and those who couldn’t, apart from their sense of smell, and any differences in death rates could be due to these other differences and not to the sense of smell at all.
‘One possibility is that poor sense of smell is a sign, perhaps an early sign, of some underlying illness – and that this illness is what leads to increased mortality.
‘Another is that poor sense of smell might itself lead to illness, perhaps because poor smell affects how food tastes, and therefore might contribute to poor nutrition which could lead to bad health.
‘Most likely, both of these possibilities, and others, could be in play.
‘So there’s clearly a lot more to be found out in future research.’
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