A team of researchers used a sniff test on a long-term study to determine the participants' capability to determine five specific scents. Participants with olfactory damage showed significantly larger chances of being diagnosed with dementia.
'Sniffin' Sticks' To Test Olfactory Damage
In 2014, a team of researchers used Sniffin' Sticks to measure participants' ability to identify certain scents. Sniffin' Sticks look like felt-tip pens that are infused with specific scents instead of ink. The results of that research revealed a link between olfactory damage and an increased risk of death within five years. Now the same team of researchers used the same method and well-validated tool but this time to find a link between olfactory damage and subsequent dementia diagnosis.
Researchers from the University of Chicago conducted the long-term study that involved 2,906 participants between the ages of 57 and 85. Participants were tasked to identify five distinct scents: peppermint, orange, rose, leather, and fish.
Among the participants, 78.1 percent had a normal sense of smell, with 48.7 percent correctly identifying all five scents and 29.4 percent accurately identifying four out of five scents. Conversely, 18.7 percent of participants were classified as hyposmic, identifying only two or three of five scents, while 3.2 percent are considered anosmic. Among the 3.2 percent anosmic participants, 2.2 percent identified just one scent, while 1 percent did not identify a single scent.
Olfactory Damage And Dementia Diagnosis
After five years, all the participants who were unable to identify a single scent were already diagnosed with dementia as well as 80 percent of participants who only identified one or two scents. Generally, researchers found that older adults with olfactory dysfunction were more than twice as likely to be diagnosed with dementia within the next five years.
The astounding results are not surprising, given the researchers' earlier study. They believe that degeneration of olfactory sense could be signs of the beginnings or progression of cognitive decline and as such should be given closer attention.
The results of the study show the importance of the somewhat-undervalued sense of smell, which is relevant in survival and could even be a marker of mental health.
"Being unable to smell is closely associated with depression as people don't get as much pleasure in life," says Jayant M. Pinto, MD from the University of Chicago, coauthor of the study.
Researchers believe that despite the results, it could still take some time before a clinical-use olfactory test could be developed. For now, their results show that greater importance should be placed in the olfactory sense, especially among people who are at risk of cognitive decline.
The study is published in the Journal of American Geriatrics Society.