Training your Sense of Smell Improves Cognitive Function

Training your memory for a strong sense of smell is associated with a slower decline in brain volume in regions important for memory, cognitive function decision-making, and speech. Odour cues might assist individuals with depression in recalling vivid memories, which could enhance their mental health symptoms.

Engaging in smell training can boost memory and activate brain areas related to cognitive function.

Your sense of smell is closely linked to memory and brain health. If someone can’t smell pumpkin pie or apple cider this season, it may signal cognitive impairment or depression.

Researchers have found that a strong ability to detect scents is associated with a slower loss of brain volume in the frontal and temporal regions,2 responsible for speech, memory, and decision-making.

“The olfactory system has the only direct superhighway access to the memory centres and the emotional centre of the brain,” Michael Leon, PhD, a professor emeritus of neurobiology and behaviour at the University of California, Irvine, said.

Training your Sense of Smell Improves Cognitive Function

Other senses take “the brain’s side streets” to stimulate the emotional and memory centres, which means the olfactory system has a bigger impact on keeping those parts of the brain healthy, he added.

People with a loss of smell can try smell training to improve their sense of smell and boost cognitive function.

Leon said smell therapy, also known as olfactory enrichment, can stimulate the brain, particularly the memory and emotional centres.

In a recent study led by Leon and funded by Procter & Gamble, researchers tested overnight smell training in older adults. Participants were randomly assigned to a control group or a test group that used diffusers with different pleasant scents—such as lemon, rose, and lavender—for two hours nightly over six months.

The test group had significant improvement in memory compared to the control group.

“We also found a similar improvement in one of the critical memory pathways in the brain when we did brain imaging on those individuals,” Leon said.

Smell Therapy May Help Treat Depression, Too

Some researchers say that exposure to different scents could help people manage mental health conditions.

In a recent study of adults with major depressive disorder (MDD)—a condition that can make it difficult to remember specific personal experiences—odour cues led to more detailed memories than word cues.

Mental healthcare providers currently use word cues to help people with MDD recall detailed memories, so these findings could lead to new, effective treatment options.

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“I am not claiming to cure depression by having people sniff things, but I am saying that by using odours, we can help them access those memories. Having access to those memories is so important for mental health that it could eventually lead to improvement in symptoms,” said Kymberly Young, PhD, a senior author of the study and an associate professor of psychiatry at the University of Pittsburgh.

The olfactory bulb, which processes smells, bypasses the brain’s prefrontal regions and sends information directly to the amygdala and hippocampus—areas involved in memory and emotion.

“Patients with depression have a lot of difficulties in recruiting these prefrontal regions, and so it bypasses these and goes directly to your memory centres. That seems to be the reason why these are such effective cues at getting rich, detailed, specific memories,” Young said.

How to Test Your Sense of Smell at Home

The University of Pennsylvania Smell Identification Test is a commercial scratch-and-sniff test you can use to reliably measure smell loss. But you can also make a DIY version using items around your home.

“You just have to go to your kitchen,” David Vance, PhD, a psychology professor at the University of Alabama at Birmingham School of Nursing, said.

Vance said you can use things like cinnamon, cocoa, vanilla extract, and lemon to test your sense of smell. Place each of those on a spoon or in a bottle and take a whiff. Scented markers can work, too.

“Those are strong, so if you can’t smell those, that’s where you might want to just tell your doctor about that and get it checked out,” he said.

Allergies, COVID-19, the flu, and colds can lead to a loss of smell. However, a healthcare provider can help you determine the cause of smell loss. If it is related to a different condition, like Alzheimer’s disease, they can help determine if olfactory enrichment can help.

“We know that people who have some vision or hearing problems, once we do some correction for that, we can see their cognitive abilities improve some,” Vance said. “The same philosophy goes with smell: If we can improve one’s ability to smell, maybe that will also have a boost [for cognitive function].”