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October 17, 2014

U of C study: Loss of scent can indicate death

A team of UChicago doctors and researchers recently published a study suggesting that olfactory dysfunction is a harbinger of death. The team’s two “scents”: Doctors need to pay closer attention to their patients’ snouts.

Olfaction and brain disease have long been linked, according to Dr. Jayant Pinto, lead author of the study and associate professor of surgery at UChicago. The study was aimed at testing the idea of scent as an indicator of overall health, not just an indicator of neurological disorders such as Alzheimer’s and Parkinson’s.

The study, a facet of the National Social Life, Health, and Aging Project (NSHAP), used “Sniffin’ Sticks,” scented felt-tip pens which were developed in Europe for clinical usage, to evaluate the olfaction of 3,005 American adults aged 57–85. In 2005–2006, participants were asked to identify peppermint- fish- orange- rose- and leather- scented sticks.

Five years later, the researchers followed up on their subjects and found that 12.5 percent of participants had died in the interim. Of those who died, the majority had performed poorly on the “Sniffin’ Sticks” test. Even those who missed only one or two scents were more likely to have died than those who missed none at all.

“The most surprising finding for me was that this effect was seen in all age groups…. Having a poor sense of smell was just as predictive of death at 5-year follow-up for people 57–64 years old as for people 75–85 years old,” graduate student and researcher David Kern wrote in an e-mail.

Kern emphasized that people are not dying because of scent loss. Rather, scent loss is an indication that the body can no longer maintain regular stem cell regeneration. This results in the body no longer being able to maintain its normal functions and keep itself healthy.

Pinto predicts that the study will lead to further research and the development of much-needed treatments in the field of olfaction. Immediately, Pinto hopes it will encourage doctors to inquire about older patients’ capacity to smell.

“This is a three-minute test that gives you a pretty good idea of whether someone needs more attention or doesn’t need more attention. We can use it to screen people for further medical testing and scrutiny, and that I think can be pretty useful,” Dr. Pinto said.

Tyler Lorig, expert on evolutionary olfaction and chair of Neuroscience at Washington and Lee University, lauded the study but cautioned that it would be hard to operationalize. “[Smell testing] will be harder to do than it sounds since one’s ability to smell declines with age. The findings made by this group show that predicting mortality requires an even greater loss than would be expected by a person age. While the research team was able to see this in their large sample, it will be a challenge to see it in individuals,” Lorig wrote.

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