How Rapid loss of smell may predict dementia and smaller brain areas linked to Alzheimer's

Jayant M. Pinto, MD, a professor of surgery at the University of Chicago and ENT specialist who studies olfactory and sinus disease, and his team wanted to see whether it was possible to identify alterations in the brain that correlated with a person's loss of smell and cognitive function over time.

The team tapped anonymized patient data from Rush University's Memory and Aging Project (MAP), a study group begun in 1997 to research chronic conditions of aging and neurodegenerative disease such as Alzheimer's disease.

The UChicago Medicine scientists found that a rapid decline in a person's sense of smell during a period of normal cognition predicted multiple features of Alzheimer's disease, including smaller gray matter volume in the areas of the brain related to smell and memory, worse cognition and higher risk of dementia in these older adults. In fact, the risk of sense of smell loss was similar to carrying the APOE-e4 gene, a known genetic risk factor for developing Alzheimer's.

The changes were most noticeable in the primary olfactory regions, including the amygdala and entorhinal cortex, which is a major input to the hippocampus, a critical site in Alzheimer's disease.

Ref:

Rachel Pacyna et. al, Rapid olfactory decline during aging predicts dementia and GMV loss in AD brain regions, Alzheimer s & Dementia, DOI: 28-Jul-2022,10.1002/alz.12717