New research suggests testing people’s ability to smell could be used to detect dementia before the symptoms become apparent. The worse their sense of smell, the bigger the risk of dementia, said researchers.
In a study that followed almost 3,000 older people with normal cognition, researchers found that a simple smell test was able to identify those at higher risk of dementia. In the study, people sniffed five different odors: peppermint, fish, orange, rose and leather.
For the “validated five-item test,” they had to identify five odors, one at a time, by sniffing a device similar to a felt-tip pen. Each time, they were given four choices, from which they had to pick out the correct one.
The researchers found that the vast majority of participants were able to correctly identify at least 4 out of 5 odors. Of the rest, 7 percent identified 2 or 3 out of 5 smells, 2.2 percent identified just one, and 1 percent could not identify any of them.
In a five-year follow-up, people who couldn’t physically detect even one of the scents all had dementia. Almost 80 percent of those who only detected one or two scents had also been diagnosed with the disease.
“Loss of the sense of smell is a strong signal that something has gone wrong and significant damage has been done,” commented Jayant M. Pinto, M.D., professor of surgery at the University of Chicago. “This simple smell test could provide a quick and inexpensive way to identify those who are already at high risk.”
“These results show that the sense of smell is closely connected with brain function and health,” Pinto said. Losing the ability to smell can have a substantial impact on lifestyle and well-being, as smells influence nutrition and mental health.
The olfactory system has self-generating stem cells and the researchers suggest that perhaps loss of sense of smell is an early sign that the brain is losing its ability to self-repair. Loss of sense of smell is often an early indicator of Alzheimer’s and Parkinson’s disease.
The authors acknowledge that more work will be needed before an olfactory test could be developed for clinical use. The study was published in the Journal of the American Geriatrics Society.