One of the earliest signs of Alzheimer’s disease has nothing to do with memory or cognition—it’s the loss of the sense of smell. Now, researchers at Case Western Reserve University School of Medicine have learned more about why the sense fails in Alzheimer’s patients and have even restored smell in lab tests.
“The evidence indicates we can use the sense of smell to determine if someone may get Alzheimer’s disease, and use changes in the sense of smell to begin treatments, instead of waiting until someone has issues learning and remembering,” says Daniel Wesson, a neuroscientist at Case Western Reserve and the study’s lead investigator. “We can also use smell to see if therapies are working.”
The body’s inability to clear naturally-occurring plaque-forming protein amyloid beta from the brain contributes to the development of Alzheimer’s and the loss of smell. Apolipoprotein E (ApoE), the main cholesterol carrier in the brain, helps clear out excess amyloid beta proteins. Bexarotene increases ApoE expression, reducing amyloid beta proteins. Bexarotene has been FDA-approved as a cancer treatment for ten years.
Within 72 hours of receiving bexarotene, test mice showed a 50% reduction in amyloid plaques and a restored sense of smell. “Understanding smell loss, we think, will hold some clues about how to slow down this disease,” Wesson says.