Ask the Doctors: Scent therapies might help preserve memory

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?

Dear Reader: You’re referring to a study published last summer in the scientific journal Frontiers in Neuroscience. Though the study was small, 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 in good physical health, none with any issues regarding cognition. They were given an odor diffuser to place 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 a night as the participants slept. 

The participants were randomly divided into two groups. One group, the control group, got liquids with just a trace of scent. The other was given liquids that contained a much higher concentration of scent. All of the participants were exposed to a rotation of seven scents — rose, orange, eucalyptus, lemon, peppermint, rosemary and lavender. 

After six months, each participant was evaluated with the standardized memory test that had been used at the start of the study. The group of adults exposed to the stronger concentrations of scent showed a 226% improvement over their previous results. Brain scans also showed positive changes. The same improvements weren’t seen in the control group, whose odor diffusers had been loaded with just a trace of scent. 

Previous research 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. 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. 

The area of the brain that receives scent signals from the nose is the olfactory bulb. It decodes those signals, then shares them with nearby structures in the brain, collectively known as the limbic system. These have been found to play a role in emotion, mood and memory. 

The UC Irvine researchers have called the results of this new study statistically significant but also said larger and longer studies are needed to confirm their findings. The hope is that scent therapies might someday become a means of enriching memory.

Dr. Eve Glazier and Dr. Elizabeth Ko are UCLA Health internists.