The nerves in our nasal cavity send signals to our brain to alert us to what we’re smelling. As we age, our sight, hearing and sense of smell diminishes. When we lose our ability to distinguish one odor from another, say vanilla versus cinnamon, it can be an early sign of dementia or Parkinson’s disease, a 2018 study in Current Asthma and Allergy Reports and a 2016 study in Neurology found.
We can lose our sense of smell temporarily, such as from a viral infection like cold, flu or COVID-19, but it usually returns. Poor odor identification in adults – the ability to distinguish one scent from another versus the overall ability to smell – has been linked to a significant increase in the risk of later dementia, according to a 2020 study in Frontiers in Neuroscience.
Diagnosing Loss of Smell
Loss of the ability to identify smells signals a dysfunction in the region of the brain responsible for identifying and naming smells, says Devangere P. Devanand, professor of psychiatry and neurology, Columbia University Irving Medical Center. But more research is underway.
“We don’t know enough about what changes in smell might mean for a person’s risk overall,” Devanand says. About 4 percent of the population, since childhood, can’t identify odors, but that has nothing to do with dementia, he adds.
