AN ELDERLY person who cannot accurately distinguish the smell of peppermint or fish may be staring death in the face, research suggests.

A study among a nationally representative sample of adults aged 57–85 found those who lost their sense of smell and were already at high risk from medical conditions had more than double the risk of dying in the next five years.

The cohort of 3000 provided baseline data by trying to identify odours, which were, in order of increasing difficulty to pinpoint, peppermint, fish, orange, rose and leather.

Five years later, the researchers assessed which participants were still alive.

Some 430, or 12.5% of the original cohort, had died.

People noted as anosmic in the first survey had a threefold increased risk of death when other factors including age, race and health were taken into consideration, the researchers said.

They noted a “dose-dependent” relationship between sense of smell and risk of death, with anosmic individuals having a greatly increased risk compared to hyposmic individuals, and the latter being more likely to die than those with a normal or “healthy” sense of smell.

The study showed 39% of anosmic individuals identified in the first test had died before the second survey. 

This compared to 19% of hyposmic people and 10% of those with a normal sense of smell.

“We believe olfaction is the canary in the coalmine of human health, not that its decline directly causes death,” the researchers wrote.

Assessment of olfactory function may be useful to help identify patients at high risk of mortality, they said.

PLoS ONE 2014; online 1 Oct