Smell test could identify Alzheimer's

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Impaired Sense of Smell May Signal Dementia Risk in Seniors

"Passing the smell test" may not just be a casual idiom anymore. New research suggests that the decreased ability to identify certain odors may signal early-stage Alzheimer's disease and future cognitive decline.

The test – dubbed the University of Pennsylvania Smell Identification Test – was the focus of two studies presented at the Alzheimer's Association International Conference in Toronto. Both studies were funded by the National Institute on Aging.

In addition to an MRI scan measuring the thickness of the brain region where Alzheimer's typically first strikes, the so-called entorhinal cortex, one of the studies used the smell test on 397 adults in Manhattan, who were 80 years old, on average, and didn't have dementia. Fifty of these people (12.6 percent) had dementia four years after undergoing the initial smell test, while nearly 20 percent showed signs of cognitive decline.

Low smell test scores, or the decreased ability to identify odors correctly, correlated with dementia and Alzheimer's disease and appeared to predict cognitive decline.

"Our research showed that odor identification impairment, and to a lesser degree, entorhinal cortical thickness, were predictors of the transition to dementia," study author Seonjoo Lee, assistant professor of clinical biostatistics (in psychiatry) at Columbia University Medical Center, said in a statement. "These findings support odor identification as an early predictor, and suggest that impairment in odor identification may precede thinning in the entorhinal cortex in the early clinical stage of Alzheimer's disease."

"Our study adds to the growing body of evidence demonstrating the potential value of odor identification testing in the detection of early-stage Alzheimer's disease," senior author of both studies D.P. Devanand, professor of psychiatry at Columbia University Medical Center, said in the same statement.

At present, Alzheimer's disease can only be clinically identified in its later stages, after the brain is severely damaged. Approximately 5.4 million Americans have Alzheimer's, according to the Alzheimer's Association.

Related: Also see notable people who had Alzheimer's Disease:

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This file photo dated 04 November, 1991 shows US President Ronald Reagan giving a speech at the dedication of the library bearing his name in Simi Valley, California. He was US president from 1981 to 1989 and retreated from public life after it was revealed he was suffering from Alzheimer's disease. (Photo by J. David Ake, AFP/Getty Images)
Glenn Campbell performs during The Goodbye Tour at the Ryman Auditorium on January 3, 2012 in Nashville, Tennessee. (Photo by Ed Rode/Getty Images)
Picture dated 18 May 1991 of US actor Charles Bronson during the 44th Cannes film festival, southern France. Bronson died 30 August 2003 in Los Angeles of complications from pneumonia. (Photo by Gerard Julien, AFP/Getty Images)
392653 01: Actor Burgess Meredith performs in the television show 'The Twilight Zone.' (Photo Courtesy of Sci Fi Channel/Getty Images)
LOS ANGELES - AUGUST 31: Actor James Doohan recieves his star on the Hollywood Walk of Fame August 31, 2004 in Los Angeles, California. (Photo by Mark Mainz/Getty Images)
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