The nose knows
An unlikely detector of Alzheimer’s disease may be no farther away than your own nose—literally.
A new study makes the case that a poor sense of smell could be the red flag indicating that Alzheimer’s is imminent. Difficulty in being able to identify common smells—such as banana, cinnamon, and lemon, some of the scents that were used on a scratch-and-sniff test—is being considered as a possible harbinger of the illness.
The test is building upon something already known about Alzheimer’s disease: The initial miniscule lesions on the brain that are part of the disease pathology actually appear in the same region that houses the sense of smell.
And while the loss of smell has been linked to the degenerative memory disease in prior studies, this is the first study of its kind to use healthy test subjects, measure their current powers of smell, and then follow them for a period of five years. Throughout that five-year time period, the participants were tested for any evidence of mental decline.
The group tested was made up of 600 healthy people between the ages of 54 and 100. They were asked to identify a dozen smells that are recognizable to just about everybody. Smells in addition to the ones I listed above were black pepper, onion, chocolate, pineapple, rose, gasoline, smoke, soap, and paint thinner. For each scent, they were asked to identify the smell from four choices.
About 25 percent of the participants were able to identify all the smells correctly or missed only one. Half of the group recognized at least 75 percent of the smells. The remaining 25 percent of those tested were able to identify only eight or fewer of the scents.
For the next five years after the initial test, the participants took 21 cognitive tests on an annual basis. Over the course of the study, about a third of the group developed mild problems with memory and thinking. Those who scored lowest on the initial smell test were also 50 percent more likely to develop memory problems than those folks who were in the top-scoring group.
Also, difficulty in identifying smells correlated with an increased risk of progressing from mild cognitive problems to full-blown Alzheimer’s—even when all other factors were taken into consideration, such as age and history of strokes.
However, the researchers cautioned that there is no need to panic if your sense of smell is not especially strong. Not everyone who had difficulty in identifying smells necessarily ended up experiencing cognitive decline. I think it’s a good idea, though, to alert your doctor if you notice a change in your sense of smell. This is the same advice I’d give if you experienced any other change in your normal habits and functioning.
Speak up!
