Could a simple smell test reveal premature ageing?

Doctors could assess elderly patients for indicators of frailty and unhealthy ageing using a simple smell test. Johns Hopkins researchers found that the loss of scent may indicate a higher risk of developing age-related health issues.

These findings, published in the Journal of Gerontology, strengthen the notion that smell dysfunction serves as an early warning sign of cognitive decline and demonstrate that there is a connection between frailty and both the brain and the nose. Researchers evaluated olfactory sensitivity and olfactory identification for this study, which refer to, respectively, the capacity to detect an odour and the capacity to identify and name an odour.

“We use our sense of smell to identify the threat of a fire or to enjoy the fragrance of flowers on a spring day. But just like vision and hearing, this sense weakens as we age,” said corresponding author Nicholas Rowan, MD, associate professor of otolaryngology, in a university release. 

“We found that both impaired olfactory identification and sensitivity functions are associated with frailty, which is interesting because it shows that it’s not just your ageing brain at work here, but it may also be something peripheral, like something at the level of your nose that is able to predict our impending frailty and death.”

Between 2015 and 2016, Rowan and the group examined data on 1,160 senior citizens who participated in the National Social Life, Health, and Aging Project. Participants in the study were exposed to five scents to gauge their ability to identify them and six odours to gauge their sensitivity. The group then compared these findings to their frailty rating.

They discovered that frailty status dramatically decreased for each olfactory identification, indicating a link between good smell and better general health in the older population. The team concludes from this that monitoring one's sense of smell may be a useful biomarker and risk factor for frailty.

According to Rowan, this research adds to the body of evidence supporting the use of smell tests as a crucial component of therapeutic care for elderly patients who may have cognitive impairments.

“We already do tests to assess how well we can see or hear, and it's just as easy to conduct a simple smell test that takes only minutes, which could potentially be used as a valuable tool to assess the risk of frailty or unhealthy ageing,” Rowan added. 

“For example, if someone flunks a smell test then maybe this patient needs to improve their nutrition or undergo a more detailed neurological or medical workup.”

Since COVID-19 affects the scent of many people globally, the Hopkins team is already investigating the use of smell tests and how they may support clinical and research initiatives to improve care for older persons.