Could a declining sense of smell be a sign of dementia?

People who have trouble recognizing the scents of mint, orange, leather, fish, and roses may struggle with dementia in the future, according to research by researchers at the University of Chicago.

The study, published in the Journal of the American Geriatrics Society, surveyed nearly three thousand people aged 57 to 85. It found that those who couldn't identify four out of five odors were more likely to develop dementia within the next five years. Those with a healthy sense of smell had a significantly lower risk.

The analysis results were as follows:

• 78% of the respondents correctly identified four out of five scents (fish, orange, mint, leather, rose),
• approximately 14% of people recognized three aromas,
• 5% of respondents identified two aromas,
• 2% of people named only one scent,
• 1% of respondents did not identify any odor.

What connection does a poorer sense of smell have with the development of dementia?

After five years, almost all of those who failed to recognize any odors had developed dementia. However, 80% of those who identified only one or two odors were diagnosed with the disease.

What can cause a deteriorating sense of smell?

Environmental factors negatively impact the olfactory nerve. Cells that detect odors are connected to the olfactory bulb at the base of the brain. This exposes the central nervous system to unfavorable external factors, such as pathogens and pollutants. Consequently, problems with the sense of smell may herald Parkinson's or Alzheimer's disease. This test helps identify individuals at higher risk. However, the study's author, Dr. Jayant M. Pinto, emphasizes that more research is needed before the test can be considered clinically relevant.