Among older people exposed to five different odours, those unable to tell the scents apart were more likely to die within five years.
Researchers described sense of smell as ‘the canary in the coal mine’ for human health.
In the study, published in PLoS ONE, researchers gave a scent test in 2005-6 to 3,005 adults aged 57-85. The test asked them to identify peppermint, fish, orange, rose and leather odours. It was repeated in 2010-11. Between the tests, 430 participants (12.5%) died.
Researchers found that 39% of those who failed the test had died, compared with just 19% of those who had only moderate loss of sense of smell, and 10% of those with healthy smell sense.
Lead author Dr Jayant Pinto from the University of Chicago, Illinois, said: ‘It doesn't directly cause death, but it's a harbinger, an early warning system, that something has already gone badly wrong, that damage has been done. Our findings could provide a useful clinical test, a quick and inexpensive way to identify patients most at risk.’