Losing Sense of Smell May Mean Early Dementia
Losing the sense of smell could be an early warning sign of Alzheimer’s disease, according to a study at the Mayo Clinic.
For their study, researchers assessed the sense of smell of 1,430 healthy participants with an average age of 79.5 years. About half of the participants were men and half were women.
The participants were part of the population-based prospective Mayo Clinic Study of Aging that took place between 2004 and 2010. It included evaluations every 15 months through 2014.
Participants were first asked to scratch, sniff and identify the food item or non-food item from four choices. The test involved six food-related scents including banana, chocolate, cinnamon, lemon, onion, and pineapple. Non-food related scents that were tested included gasoline, paint thinner, soap, smoke, and turpentine.
Over the course of the 3.5-year follow-up, the researchers identified 250 new cases of mild cognitive impairment (MCI) among the 1,430 participants.
Additionally, 64 dementia cases among 221 individuals with MCI were reported. And the worst smell test scores were associated with progression from mild dementia to Alzheimer’s Disease.
The findings, published in the journal JAMA Neurology, confirm previous autopsy studies that linked a decrease in the ability to smell with cognitive impairment.
Possible explanations are that there are degenerative changes in the olfactory bulb and brain regions that involve memory and sense of smell.