Rapid loss of smell could be early indicator of dementia

Rapid loss of smell could be an early indicator of dementia and Alzheimer’s disease in older adults. Olfactory testing may show promise for clinicians in monitoring and treatment of cognitive decline, according to a new study.

Researchers from the University of Chicago studied 515 older adults from the Rush University Memory and Aging Project to assess the connection between the loss of smell and cognitive decline in older adults.

The researchers hypothesized that older adults with rapid decline in the sense of smell would have smaller gray matter volumes (GMV), worse subsequently impaired cognition, and more frequent diagnoses of mild cognition impairment and Alzheimer’s disease than those with slower or no olfactory decline. They concluded that faster olfactory decline was associated with higher incidence of subsequent mild cognitive impairment and dementia and smaller gray matter volume for those with Alzheimer’s disease.

“Our idea was that people with a rapidly declining sense of smell over time would be in worse shape — and more likely to have brain problems and even Alzheimer’s itself — than people who were slowly declining or maintaining a normal sense of smell,” Rachel Pacyna, a medical student at the University of Chicago Pritzker School of Medicine and lead author of the study, said in a statement.

The study’s authors noted that rapid loss of smell could be a promising early biomarker of Alzheimer’s disease due to the ease of testing, noting that the Brief Smell Identification Test is a non-invasive, safe and reliable test that takes only about five minutes to complete.

“Serial olfactory testing could be an accessible, pragmatic method for monitoring rate of olfactory decline as a proxy for neurodegeneration in the brain and predictor for subsequent cognitive impairment and dementia,” the authors wrote. 

The study, entitled “Rapid olfactory decline during aging predicts dementia and GMV loss in AD brain regions,” appeared in the July 28 issue of Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.