Inability to Smell Common Scents May Point to Dementia, Study Finds

By | September 29th, 2017

Scientists explore the loss of smell as a possible sign of dementia.

It’s hard to predict who dementia will strike. Genetics can give a clue, and lifestyle factors can have an influence, but a diagnosis of dementia often comes suddenly and leaves those it affects dumbfounded and shocked. But what if you could sniff out dementia before it begins?

In a study of almost 3,000 older people without dementia, those who could not identify four out of five common odors like peppermint, leather, orange, rose and fish were twice as likely to develop dementia over the next five years than those who had a normal sense of smell.

“Our test simply marks someone for closer
attention. Much more work would need
to be done to make it a clinical test.”

Researchers tested adults between the ages of 57 and 85 using a tool called “Sniffin Sticks,” a pen-like stick infused with a scent. Seventy-eight percent of them tested normal, correctly identifying four or more scents. But other test results showed that:

  • 14 percent could name three out of five scents
  • 5 percent could name two out of five scents
  • 2 percent could name just one scent
  • 1 percent could not identify any smells
For the study, scientists used a well-validated tool called “Sniffin Sticks.” Credit: Rob Kozloff, for the University of Chicago Medicine

When researchers checked back in five years later, almost all of the participants unable to name a single scent had dementia. Eighty percent of those who were able to name one or two scents had dementia.

However, researchers stress that this is not a diagnostic test. “Our test simply marks someone for closer attention,” said Jayant M. Pinto, MD, a professor of surgery at the University of Chicago and ENT specialist who studies the genetics and treatment of olfactory and sinus disease. “Much more work would need to be done to make it a clinical test. But it could help find people who are at risk. Then we could enroll them in early-stage prevention trials.”

Study: Is Beta-Amyloid the Culprit
For the Loss of Smell in Alzheimer’s? 

There are many reasons why a person might lose their sense of smell, but nonetheless, scientists say it’s alway a cause for concern. “Loss of the sense of smell is a strong signal that something has gone wrong and significant damage has been done,” Pinto said. “This simple smell test could provide a quick and inexpensive way to identify those who are already at high risk.”

“This simple smell test could provide a quick
and inexpensive way to identify
those who are already at high risk.”

Sense of smell has long been connected to cognition. The olfactory system has cells that self-regenerate, said study co-author Martha K. McClintock, PhD, a professor of psychology at the University of Chicago. A decline in sense of smell might be a signal that the brain is failing to “rebuild key components,” said McClintock, which can lead to the changes in the brain that kickstart dementia.

Read the full study here.

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