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Dear Doctors: My husband and I just hit 65 and are interested in information about preserving memory. I just read about a study that says using your sense of smell more often can be helpful. Do you have any information about that study? The details have been pretty vague.
Dear Reader: You’re referring to the findings of a study published last summer in the scientific journal Frontiers in Neuroscience. Although the study was small, the results were quite intriguing. Researchers from the University of California, Irvine found that when older adults were exposed to a range of different scents each night, their memories measurably improved.
The study looked at 43 adults ranging in age from 60 to 85. All were in good physical health, and none had any issues with cognition. Each participant was issued an odor diffuser to be placed in their bedrooms. When filled with the various liquids provided by the researchers, these devices would distribute a scent throughout the bedroom for two hours each night as the participants slept.
The study participants were also randomly divided into two groups. One group, which served as the control group, received liquids with just a trace of scent. The other group was given liquids that contained a much higher concentration of scent. Over the course of the study, all of the participants were exposed to a rotation of seven scents — rose, orange, eucalyptus, lemon, peppermint, rosemary and lavender.
At the end of the six-month period, each of the participants was evaluated with the same standardized memory test that had been used at the start of the study. The group of adults who had been exposed to the stronger concentrations of scent each night showed a 226% improvement over their previous test results. Brain scans also showed positive changes in that group. The same improvements were not seen in the control group, whose odor diffusers had been loaded with just a trace of scent.
Previous research has also linked having a good sense of smell to a slower loss of brain volume and a decrease in the rate of cognitive decline in older adults. At the same time, a decline in the sense of smell has been found to be an early symptom of neurodegenerative diseases such as Parkinson’s and Alzheimer’s.
As for why scent and memory are linked, anatomy appears to play a role. The area of the brain that receives scent signals from the nose is known as the olfactory bulb. It decodes those signals, then shares them with nearby structures in the brain, which are collectively known as the limbic system. These have been found to play a role in emotion, mood and, yes, memory.
The UC Irvine researchers have called the results of this new study statistically significant. However, they have also been careful to point out that larger and longer studies are needed to confirm the findings. The hope is that, with the encouraging results in this avenue of inquiry, scent therapies may someday become a viable means of enriching memory.