How do you keep your memory sharp in old age? Try going to bed and smelling the roses, according to scientists.
A new study published in the journal Frontiers in Neuroscience details how exposing adults between the ages 60 and 85 to different odors while they slept dramatically boosted their cognitive capacity — providing a hopeful avenue of staving off dementia (and maybe some incentive for you to buy a new candle).
"The idea is that it will keep the memory centers of your brain in good condition throughout life, and perhaps prevent memory loss older in life," said co-author Michael Leon, a professor of neurobiology and behavior at the University of California, Irvine Center for the Neurobiology of Learning and Memory (CNLM), in an interview with NPR.
You might even yourself be familiar with smell's powerful link to memory — maybe you've heard of a Proustian rush? An errant whiff of a perfume could suddenly dredge up long-forgotten episodes, the same way a taste of food can conjure up a feeling someone thought they'd lost forever, for example.
"The olfactory sense has the special privilege of being directly connected to the brain's memory circuits," explained Michael Yassa, a fellow neurobiology professor at CNLM, in a statement.
"However, unlike with vision changes that we treat with glasses and hearing aids for hearing impairment, there has been no intervention for the loss of smell."
In the study, researchers drew from a small pool of 43 participants not suffering from memory loss, who they divided into two groups. One group received a natural oil diffuser and seven powerful fragrance cartridges: rose, orange, eucalyptus, lemon, peppermint, rosemary, and lavender.
The control group, not as lucky, were given "sham" cartridges with barely any scent.
Over the course of six months, all participants were instructed to diffuse a different cartridge before going to bed, emitting either pleasant odors or almost nothing at all for two hours while they dozed off.
And voila: by the end of the study, the adults with the scents showed a remarkable 226 percent improvement in cognitive performance, evaluated via a word learning test, and backed-up by imaging that revealed strongly functionality in a brain pathway associated with the formation and retrieval of memories.
It's worth noting that scientists have known that the loss of olfactory senses can predict the onset of dementia and other neurological diseases. Using smell as a memory booster in such patients has also been explored before, with one previous study finding moderate dementia patients could benefit from being exposed to 40 different smells twice per day.
"But it's not realistic to think people with cognitive impairment could open, sniff and close 80 odorant bottles daily," Leon said in the statement.
Instead, what this new research demonstrates is that exposure can be done passively, i.e. in your sleep, using far fewer odors. In other words, it's a lot more practical — but further research using a much larger sample size and, ideally, on those with diagnosed memory loss, will be needed before any of this smell science is set in stone.
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