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In the search for easy-to-perform tests to predict Alzheimer’s disease risk, new research suggests the nose might know and the eyes might have it. “Older patients are more and more often
asking their doctors if they’re going to get Alzheimer’s disease,” William Kreisl , a Columbia University Medical Center neurologist, said at a briefing Tuesday at the Alzheimer’s
Association International Conference (AAIC) in Toronto. Detection of the disease before symptoms appear would enable people to make decisions about their care while they still can, said
Melanie Campbell of the University of Waterloo in Ontario. “We’re on the cusp of new therapies for Alzheimer’s disease,” so the earlier patients could begin taking them, the greater the
chance they could work, added Suzanne Craft, an Alzheimer’s researcher at the Wake Forest School of Medicine. Both the nose and the eyes can serve as windows into what’s going on in the
brain. Researchers at the University of Pennsylvania have developed the University of Pennsylvania Smell Identification Test (UPSIT), an inexpensive scratch-and-sniff test that people can
take on their own on in a doctor’s office. Low UPSIT scores have been shown to predict cognitive decline in people with no symptoms as well as in those with memory problems, Kreisl said. The
sense of smell is connected to areas of the brain affected early on in Alzheimer’s disease, he said. Kreisl and his colleagues compared UPSIT scores with beta-amyloid status in 84 adults
who were age 68 on average. Beta-amyloid deposits are made of protein fragments, and their presence in the brain is a hallmark of Alzheimer’s disease. The people in his study all took the
UPSIT and underwent either a PET scan or a spinal tap. Those with an UPSIT score below 35 (out of 40) were three times more likely to have memory decline six months later than those with
higher scores. In a related study, other Columbia scientists administered UPSIT to 397 people, age 80 on average, who also underwent MRI brain scans. They found that people with low UPSIT
scores were more likely to develop dementia during a follow-up period of four years. To a lesser degree, the MRI scans showed that thinning in the entorhinal cortex, the first part of the
brain to be affected by Alzheimer’s, was also associated with a greater risk of developing dementia. The eye might also prove to be an accessible avenue for assessing the status of amyloid
in the brain, Campbell’s study found. She and her collaborators examined the eyes of patients with and without Alzheimer’s who had donated their organs to science. Using polarizing
microscopes, the researchers found amyloid deposits in the retinas of those who had Alzheimer’s. Polarization imaging of the eye is a promising tool for detecting amyloid deposits before
Alzheimer’s symptoms appear, Campbell said. Another promising imaging technology is optical coherence tomography, or OCT, which one study presented at the Alzheimer’s meeting used to assess
amyloid in the retina, the light-sensitive tissue at the back of the eye. Ophthalmologists regularly use OCT to diagnose diseases such as age-related macular degeneration, diabetic
retinopathy and glaucoma.