Elderly can't identify odours

Scientists, studying how the sense of smell changes as people age, have found that olfactory sensory neurons in those 60 and over showed an unexpected response to odour that made it more difficult to distinguish specific smells, putting them at greater risk from dangerous chemicals and poor nutrition.

“We found clear changes in olfactory sensory neuron responses to odours for those 60 and up. When we presented two different odours to the olfactory sensory neurons of younger people they responded to one or the other.

“The sensory neurons from the elderly responded to both. This would make it harder for the elderly to differentiate between them,” said lead scientist Prof Diego Restrepo at the University of Colorado School of Medicine. Those losing their sense of smell are at higher risk of malnutrition since taste and smell are closely related, and they may also be unable to detect spoiled food, leaking gas or toxic vapours.

The scientists looked at 440 subjects in two age groups — those 45-years-old and younger and those 60 and over. Their olfactory sensory neurons (OSNs) were tested for their responses to two distinct odours.

“Whereas cells from younger donors were highly selective in the odorants to which they responded, cells from older donors were more likely to respond to multiple odour stimuli suggesting a loss of specificity,” the scientists said.

They had expected to find less OSNs in older subjects and they thought the neurons would be less likely to respond to stimuli. In fact, they found as many neurons in the old as the young but those over 60 could not differentiate between two odours.