A new study suggests that the inability to detect certain smells could be a possible dementia symptom in older individuals.
In order to determine how an elderly person's sense of smell could affect their risk of dementia, a team of researchers from the University of Chicago had close to 3,000 men and women aged 57 to 85 take part in a small test. According to the New York Daily News, the participants were given "Sniffin' Sticks" felt pens infused with the scents of fish, leather, orange, peppermint, and rose, and asked if they could identify the smells associated with the pens.
Based on the study's results, more than three-fourths of the men and women had a normal sense of smell, with half of the participants able to identify all five smells correctly. Another 18.7 percent were identified as "hyposmic," as they only got two or three odors right. Lastly, 3.2 percent were found to be "anosmic," having identified one or none of the smells.
Five years after the smell test, it was revealed that almost all of the participants who identified two scents or fewer had dementia or its symptoms. Those who weren't able to correctly identify a single smell were all diagnosed with dementia at that time, and some even required a proxy to take the survey, as they were too ill to physically participate.
In a statement, study lead author Dr. Jayant Pinto said that the smell test could be helpful in determining a person's risk of dementia, though further research may be needed.
"Our test simply marks someone for closer attention. 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."
Although the study suggests that an inability to sniff out certain odors could be one of dementia's symptoms, a few experts who weren't involved the study were cautiously optimistic, but not completely in favor of having doctors conduct smell tests to determine dementia risk in patients.
Speaking to Newsweek, NYU Langone Center for Brain Health director Dr. Mony de Leon described the study as "interesting," and commended the researchers for getting a large number of people to participate. He did, however, warn that the study is "not ready for prime time," even if he saw it a mostly solid piece of research.
Similarly, Mayo Clinic neurologist Dr. Ronald Petersen cautioned that the smell test should not be used by doctors as a standalone method for determining if a person has dementia or not. But he added that the study's findings could have some merit if the smell test is used in conjunction with tests that analyze a person's gait and vision.
"Simple, cheap screening measures might separate people into high, medium and low risk," said Petersen, who also serves as director of the Mayo Clinic's Alzheimer's Disease Research Center and Study of Aging.
"These combinations are giving you real, predictive values that are going to be useful."The new study is not the first of its kind to identify a failing sense of smell as a possible dementia symptom. Medical News Today detailed a 2015 study from the Mayo Clinic that used similar methodologies and a wider range of scents, and also revealed that anosmia, or olfactory loss, might be a marker for the onset of certain types of dementia, including Alzheimer's disease.
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