Older adults who want to improve their memory are usually advised to learn new skills, stay physically active, and maintain a healthy diet. Now, another recommendation has been added to the list based on new research: regularly stimulating your sense of smell can boost your memory.
Fragrances play an important role in forming and retaining memories, according to a study conducted by Michael Leon, professor emeritus of neurobiology and behavior at the University of California, Irvine, Charlie Dunlop School of Biological Sciences. The study found that scents that trigger positive emotions can improve people’s cognitive functions, such as the ability to remember details and use words from memory with ease. What’s more, finding fragrances isn’t that difficult. For example, Leon used a diffuser with pleasant-smelling oils in his study.
According to Leon’s research, the olfactory system, which is responsible for the sense of smell, has a “direct superhighway” into the hippocampus, the brain’s memory center, more so than the other senses. The hippocampus can permanently save a smell that it deems important, particularly if it’s linked to a significant emotional event. The same scent can bring back memories even years later.
The other senses (vision, hearing, taste, touch) pass through the thalamus, which acts as the brain’s central relay station, routing nearly all sensory information to the cerebral cortex for processing. Scents bypass these “side streets” and allow odor-based stimulation to significantly improve memory.
Researchers say that having a “direct superhighway” to the brain’s memory center is why experts who undergo intensive smell training—like sommeliers (wine specialists)—develop stronger memory-related brain regions because they constantly train their sense of smell.
What’s more, the olfactory system deteriorates if it’s not regularly stimulated, much like an unused muscle. In fact, the first sign of Alzheimer’s disease is often a reduced sense of smell. Scientists say that regular stimulation of the olfactory system can possibly provide greater resistance to neurodegenerative diseases, such as Alzheimer’s.
Other Studies Conducted On Smell-Memory Connection
Leon’s is not the first study to focus on the connection between smell and memory. In a 1935 paper titled “What Can You Do with Your Nose?” psychologist Donald Laird posed the question of whether the sense of smell, which he argued was largely overlooked by educators and scientists, could be a key “avenue into the mind” and a powerful trigger for emotion-filled memories.
Laird and his colleagues surveyed 254 people, collecting their anecdotes on how scents trigger vivid, deep-seated emotional memories, which he described as more than just “casual will-o’-the-wisps in our mental fabric.”
Many of the participants reported these memories as among their most intense. For example, one participant was the son of a sawmill worker who reported that the smell of sawdust brought on “a series of vivid pictures so graphic that for the moment I live the scenes again.”
Laird was only guessing at the connection then, but scientists today are making progress in understanding it and how to use it to improve health.
“It’s now clear that even though our sense of smell is not as robust as that of a mouse or bloodhound, it is deeply tied to our cognitive centers, our emotional centers, and our memory centers,” Sandeep Robert Datta, a professor of neurobiology at Harvard Medical School, told Harvard Medicine Magazine. “We’re dependent on it for a sense of well-being and centeredness in the world.”
About Leon’s Study
Since a lack of olfactory stimulation impaired memory, Leon launched a research project to determine whether increasing olfactory stimulation could improve it. The study, published in Frontiers in Neuroscience, involved 43 men and women aged 60 to 85 who had no memory impairment and were in good general health.
The participants were randomly assigned to two groups, an olfactory-enriched group and a control group. For six months, participants in the enriched group were exposed to seven different scents for two hours each night as they slept. The control group received much smaller amounts of the scents. Assessments and MRI scans were given at the beginning of the study and after six months.
Leon and his team discovered a 226 percent increase in memory in the enriched group compared to the control group. According to the researchers, exposure to a range of scents functions like physical therapy for the brain.
“As far as we know, this is the largest memory improvement in healthy adults ever reported,” Leon said in a press release.
A similar study involving people with dementia found up to a 300 percent improvement in their memory on standard tests.
“This is the most effective treatment for dementia and Alzheimer’s disease by a mile,” Leon said. “Nothing else comes close.”
Although Leon’s research found that stimulating the olfactory system with different scents can dramatically improve older adults’ memory, it’s not practical to use 40 or more scents every day. And even if older adults want to be exposed to aromas while they sleep, a diffuser can only deliver one scent at a time.
According to Leon and Bernstein, the scents cannot be released too close together to avoid blending into a “scent soup,” which would make the therapy ineffective. To address this issue, they partnered with Spanner, a Silicon Valley engineering company, to create a rotating belt of individual scent pods, each heated and released in sequence.
The positive effects scents have might be the reason why losing the sense of smell, known as anosmia, can negatively impact a person’s mental health.
“If we are suddenly denied our sense of smell, we feel adrift and confused about where we are in a way we didn’t expect,” Datta told Harvard Medicine Magazine. “We’re constantly being reminded about where we’ve been and where we are through our sense of smell.”
Besides protecting the brain, some studies show smells that trigger personal memories also reduce stress and inflammation, improve mood, and promote slower, deeper breathing than “pleasant but more generic smells,” according to Rachel Herz, a neuroscientist at Brown University who studies the psychological science of smell.
“Smell can instantly trigger an emotional response along with a memory, and our emotional states have a very strong effect on our physical well-being,” Herz told Harvard Medicine magazine.
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