Aside from forgetfulness or confusion behind the wheel, there is another major (and oft-forgotten!) sign of dementia: smell. For instance, scientists recently discovered that the inability to distinguish these two surprising scents might be one of the earliest signs of Alzheimer’s. And according to new research published in the Journal of the American Geriatrics Society, failing to identify a few particular smells could indicate your risk, too.
In a long-term study of nearly 3,000 adults aged 57 to 85, researchers found that those who could not identify at least four out of five smells (peppermint, fish, orange, rose, and leather) were more than twice as likely to develop dementia five years later.
For the study, researchers asked the volunteers to smell “Sniffin’Sticks”—felt-tipped sticks that are infused with fragrances—and identify each scent from a list of four choices. They arranged the five smells, including peppermint, fish, orange, rose, and leather, in order of increasing difficulty.
Seventy-eight percent of the study subjects correctly recognized at least four out of five scents, the researchers reported. However, about 14 percent only identified three out of five, five percent could name just two smells, and two percent named one. One percent of participants could not identify any of the scents.
Five years later, the research team checked in with their participants. What did they find? Almost all of the study subjects who failed to name a single scent had been diagnosed with dementia. And nearly 80 percent of those who could identify only one or two fragrances had dementia, too.
“These results show that the sense of smell is closely connected with brain function and health,” said the study’s lead author, 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. “We think smell ability specifically, but also sensory function more broadly, may be an important early sign, marking people at greater risk for dementia.”
Previous research has shown that the parts of the brain associated with the sense of smell, including the olfactory bulb and entorhinal cortex, are often the first to be affected by dementia and Alzheimer’s disease. The ability to smell continues to decline as the condition progresses, experts say.
If you’re worried about your own risk, neurologists say these daily habits can sharpen your brain and prevent Alzheimer’s disease down the road.