Oct 31, 2016

Can a Smell Test Predict Early Stages of Alzheimer’s Disease?

Researchers report that an odor identification test may prove useful in predicting cognitive decline and detecting early-stage Alzheimer’s disease.

Could a smell test be a useful tool in memory care and dementia care?
By Alzheimer's Reading Room

I wrote about the smell test many times here in the Alzheimer's Reading Room. It interests me not only because it would be a good way to detect Alzheimer's; but also I think it relates to why it is often difficult to get dementia patients to eat more food.

Thing about it? What usually happens when you smell food cooking? If it smells good - you get hungry. Those saliva glands get in action.

When I first read about this way back in 2004, I asked my mother if she could smell this and that. I often wondered what would have happened if I had read the article in 2000? Would I have given my mother the smell test? If so, and she couldn't smell things would I have taken action with her doctor? I'll never know.

One thing I do know. If a person starts having memory problems it would probably be a good idea to bring this up with a good doctor well versed in dementia research and dementia care.

You might consider passing this information along if you live in a community of seniors.

How to Get Answers To Your Questions About Alzheimer's and Dementia

Smell Test May Predict Early Stages of Alzheimer’s Disease

Researchers from Columbia University Medical Center (CUMC), New York State Psychiatric Institute, and NewYork-Presbyterian reported that an odor identification test may prove useful in predicting cognitive decline and detecting early-stage Alzheimer’s disease.
  • Their two studies suggest that the University of Pennsylvania Smell Identification Test (UPSIT) may offer a practical, low-cost alternative to other tests.
In one study, researchers administered UPSIT to 397 older adults (average age of 80 years) without dementia from a multiethnic population in northern Manhattan.

Each of the participants also had an MRI scan to measure the thickness of the entorhinal cortex—the first area of the brain to be affected by Alzheimer’s disease.
  • Four years later, 50 participants 12.6 percent) had developed dementia and nearly 20 percent had signs of cognitive decline.
  • The researchers found that low UPSIT scores, but not entorhinal cortical thickness, were significantly associated with dementia and Alzheimer’s disease. (Low UPSIT scores indicate decreased ability to correctly identify odors.)
Low UPSIT scores, but not entorhinal cortical thickness, also predicted cognitive decline, although entorhinal cortical thickness was significantly associated with UPSIT scores in those who transitioned to dementia.
Our research showed that odor identification impairment and, to a lesser degree, entorhinal cortical thickness were predictors of the transition to dementia.  “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.” - Seonjoo Lee, PhD, assistant professor of clinical biostatistics (in psychiatry) at Columbia.

In another study, researchers from CUMC evaluated the usefulness of UPSIT and tests that measure the amount of amyloid in the brain (in higher amounts, the protein forms plaques in the brains of those with Alzheimer’s disease) in predicting memory decline.
  • The researchers administered UPSIT and performed either beta amyloid PET scanning or analysis of cerebrospinal fluid in 84 older adults (median age of 71 years). 
  • Of these, 58 participants had mild cognitive impairment. The researchers followed the participants for at least six months.
  • At follow-up, 67 percent of the participants had signs of memory decline. 
Testing positive for amyloid with either method, but not UPSIT score, predicted cognitive decline.

However, participants with a score of less than 35 were more than three times as likely to have memory decline as those with higher UPSIT scores.
Our research suggests that both UPSIT score and amyloid status predict memory decline.  Younger age, higher education, and shorter follow-up may explain why UPSIT did not predict decline as strongly in this study as in previous studies. Although more research is needed, odor identification testing, which is much less expensive and easier to administer than PET imaging or lumbar puncture, may prove to be a useful tool in helping physicians counsel patients who are concerned about their risk of memory loss.” - said William Kreisl, MD, Professor of Neurology (in the Taub Institute) and a neurologist at NewYork-Presbyterian/Columbia.
Current methods are only capable of clinically detecting Alzheimer’s disease in the later stages of its development, when significant brain damage has already occurred. 
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,” said D.P. Devanand, MD, professor of psychiatry (in neurology and in the Gertrude H. Sergievsky Center) at CUMC and senior author of both studies.

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“Predictive Utility of Entorhinal Cortex Thinning and Odor Identification Test for Transition to Dementia and Cognitive Decline in an Urban Community Population” by Seonjoo Lee, PhD, et al., was funded by the National Institute on Aging, grants K01AG051348, R01AG034189, R01AG037212, K99/R00AG042483, R01AG041795.

“Both Odor Identification and Amyloid Status Predict Memory Decline in Older Adults” by William Kreisl, MD, et al., was funded by the National Institute on Aging, grants R01AG17761 and R01AG041795.

Columbia University Medical Center is home to the largest medical research enterprise in New York City and State and one of the largest faculty medical practices in the Northeast. For more information, visit cumc.columbia.edu

The Taub Institute has been designated as a Center of Excellence for Alzheimer’s Disease by the New York State Department of Health. For more information, visit The Taub Institute at http://www.cumc.columbia.edu/dept/taub/.

New York State Psychiatric Institute (founded in 1896) and the Columbia University Department of Psychiatry have been closely affiliated since 1925.

NewYork-Presbyterian is one of the nation’s most comprehensive healthcare delivery networks, focused on providing innovative and compassionate care to patients in the New York metropolitan area and throughout the globe.