Smell and eye tests may be next step in diagnosing Alzheimer's

New evidence released Tuesday suggests the potential use of two cheaper and simpler tests for detecting Alzheimer’s in patients.

At the Alzheimer’s Association International Conference in Toronto, researchers presented the results of four studies that investigated the use an odor test and an eye test in diagnosing cognitive problems and Alzheimer’s disease in patients at an earlier stage.

Currently, it is only possible to diagnose Alzheimer’s using PET scans or Lumbar punctures. However, these methods are expensive and invasive, and are only able to detect Alzheimer’s later in its development, researchers argued in a news release detailing the studies’ findings.

In the release, investigators said they hoped the new studies would lead to cheaper alternatives to tests that are currently being used for Alzheimer’s detection.

“It’s clear that the science around biological measures in the detection of Alzheimer’s continues to gather pace and validation,” Heather Snyder, Ph.D., senior director of medical and scientific operations for the Alzheimer’s Association, said in the release. "Low-cost, non-invasive measures to detect dementia-related changes and evaluate the risk of future decline continue to be refined and tested; this is a positive step forward to earlier detection and intervention."

Two of the presented studies focused on odor identification and its relationship to cognitive decline in patients.

Researchers at Columbia University Medical Center administered the University of Pennsylvania’s Smell Identification Test (UPSIT) — a commercially available test used to assess an individual’s sense of smell — to 397 patients for four years.

The goal, researches said, was to better understand the use of an odor test for detecting the onset of dementia and cognitive decline in patients. Ultimately, researchers discovered that lower UPSIT scores were associated with early stages of Alzheimer’s and dementia in patients.

“While more research is needed, because the UPSIT is much less expensive and easier to administer than PET imaging or lumbar puncture, odor identification testing may prove to be a useful tool in helping physicians counsel patients who are concerned about their risk of memory loss,”  Dr. William Kreisl, assistant neurology professor and a physician at Columbia University Medical Center, said in the release.

Researchers also presented results from two studies outlining the use of apparent changes in and around the eye in identifying patients with Alzheimer’s.

One study, which analyzed the results of a physical examination, a cognitive test, and a questionnaire in 33,068 participants, found that a thinner retinal nerve fiber layer (RNFL)— an extension of fibers from the optic nerve that sends visual information from the retina to the brain— was associated with poorer cognition.

The research team from the University College of London Institute of Ophthalmology, Topcon Advanced Biomedical Imaging Laboratory in Oakland, New Jersey, and the University of Oxford, found that individuals who showed an abnormal cognitive test had a thinner RNFL than those who had normal cognitive tests.

RNFL thickness can be detected using simple medical imaging technology.

A second study, which analyzed the eyes of 20 individuals, post-mortem, who had been diagnosed with Alzheimer’s, found the presence of amyloid beta deposits in the retina.

The test used non-invasive polarized light to determine the presence of amyloid beta, which is a protein typically found in the brains of individuals with Alzheimer’s.

The researchers, from the University of Waterloo, the University of Rochester, the University of British Columbia, Massachusetts General Hospital, Vivocore Inc. and Intervivo Solutions, said in the release that they hope these results would aid in the development of less invasive and more inexpensive Alzheimer’s testing.

“Many older adults routinely visit their ophthalmologist,” Snyder said in the release. “So incorporating this technology— once proven— into annual eye care visits could aid in assessing cognitive status and identifying individuals that should have further evaluation by a health care professional.”

Researchers asserted these findings may help detect dementia and Alzheimer’s much earlier in patients and thus advance their treatments.

“Using other biomarkers of Alzheimer’s disease to detect the disease at an earlier stage, which have the potential to be lower-cost and non-invasive, could lead to dramatic improvements in early detection and management of the disease,” Snyder said in the release.