As your sense of smell begins to decline, it’s possible that your dementia risk may be surging upward, a new study suggests.
Over a five-year period, researchers tested nearly 3,000 adults aged 57 to 85, asking them to identify five common odours: peppermint, fish, orange, rose and leather. Those who couldn’t identify at least four of those were more than twice as likely to develop dementia within five years as those with a normal sense of smell.
The results suggest that sense of smell is closely connected with brain function, according to the study’s lead author, Dr Jayant Pinto.
More research needs to be done to understand the underlying mechanisms, he emphasises, but what they do know is that the cells that detect smells connect directly with the olfactory bulb at the base of the brain. This olfactory bulb is part of the brain's limbic system, which controls not only sense of smell, but also emotions and memory.
“We think a decline in the ability to smell, specifically, but also sensory function more broadly, may be an important early sign, marking people at greater risk for dementia,” he says.
Losing your sense of smell as you get older is common—a study in the Postgrad Medicine Journal notes that more than 75% of people over age 80 have some type of olfactory impairment—and can cause issues beyond potential dementia risk.
Nutritionist Joy Dubost notes that people who have trouble with smell can have a higher incidence of nutrition deficiencies, since smell and the sense of taste are so strongly linked. (These 10 groups of people are more prone to vitamin D deficiency.) They’re also more likely to have negative food reactions since they can’t smell when food has gone bad.
“When you can’t fully smell or taste food, you tend to be in a difficult position, because on a minor level, you might oversalt your food, but more seriously, you could be setting yourself up for food poisoning,” she says.
That’s why it’s important to talk to your doctor when you begin to notice your ability to smell is being affected, Pinto says. Many times, there may be an easily treatable cause, like allergies or nasal polyps.
“Of all human senses, smell is the most undervalued and underappreciated, until it’s gone,” he says. Making sure to keep your sniffer healthy and happy can go a long way toward overall wellness.
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