Simple fragrance release boosts memory in elders

Neuroscientists at the University of California, Irvine (UCI) have found that releasing aromas into the bedrooms of sleeping elders helps to increase cognitive capacity — a finding that appears to transform the long-known tie between smell and memory into a non-invasive technique for strengthening memory and potentially deterring dementia.

Scientists have long known that the loss of olfactory capacity, or ability to smell, can predict development of nearly 70 neurological and psychiatric diseases, including Alzheimer’s. Researchers have previously found that exposing people with moderate dementia to up to 40 different odours twice a day boosted their memory and language skills, eased depression and improved their olfactory capacities. Researchers from the UCI Center for the Neurobiology of Learning & Memory (CNLM) decided to turn this knowledge into an easy dementia-fighting tool.

“The reality is that over the age of 60, the olfactory sense and cognition starts to fall off a cliff,” said UCI Professor Michael Leon. “But it’s not realistic to think people with cognitive impairment could open, sniff and close 80 odorant bottles daily. This would be difficult even for those without dementia.”

Through their study, which was supported by Procter & Gamble and published in the journal Frontiers in Neuroscience, the team supplied cognitively healthy adults aged 60 to 85 with a diffuser and seven cartridges, each containing a single and different natural oil. People in the enriched group received full-strength cartridges, while control group participants were given the oils in tiny amounts. Participants put a different cartridge into their diffuser each evening prior to going to bed, and it activated for two hours as they slept.

“We reduced the number of scents to just seven, exposing participants to just one each time, rather than the multiple aromas used simultaneously in previous research projects,” said project scientist Cynthia Woo. “By making it possible for people to experience the odours while sleeping, we eliminated the need to set aside time for this during waking hours every day.”

People in the enriched group showed a whopping 226% increase in cognitive performance compared to the control group over a six-month period, as measured by a word list test commonly used to evaluate memory. Imaging revealed better integrity in the brain pathway called the left uncinate fasciculus, which connects the medial temporal lobe to the decision-making prefrontal cortex and becomes less robust with age. Participants also reported sleeping more soundly.

The researchers said the results from their study bear out what scientists have learned about the connection between smell and memory, with CNLM Director Professor Michael Yassa noting, “The olfactory sense has the special privilege of being directly connected to the brain’s memory circuits; all the other senses are routed first through the thalamus.”

The team would next like to study the technique’s impact on people with diagnosed cognitive loss. They hope their finding will lead to more investigations into olfactory therapies for memory impairment.

“Everyone has experienced how powerful aromas are in evoking recollections, even from very long ago,” Yassa said. “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.”

Image credit: iStock.com/fizkes