In a new study by neuroscientists from the University of California, Irvine (UCI), a seemingly simple fragrance diffusion method has been found to dramatically boost memory in older adults. The results suggest that the powerful connection between scent and memory can be used to combat cognitive decline and possibly even prevent dementia.
Over a six-month period, the researchers exposed participants to a different fragrance each night for two hours as they slept. The outcome of this research revealed a substantial 226% increase in cognitive capacity compared to the control group,
The research, conducted through the UCI Center for the Neurobiology of Learning & Memory, focused on a group of participants aged between 60 and 85 years who showed no memory impairments.
Scientists gave the participants a diffuser along with seven cartridges. Each cartridge contained a different natural oil. For those in the “enriched’ group,” the cartridges were full strength, while the control group received the same oils, but in significantly reduced quantities.
They introduced a different cartridge into their diffuser every evening before retiring for the night. The diffuser released its scent for two hours as they slumbered.
The findings were significant. Those in the enriched group showed a 226% increase in cognitive performance compared to the control group. They measured this using a common evaluation tool: a word list test.
Brain imaging further revealed improved integrity in a pathway known as the left uncinate fasciculus. This is a vital connection between the medial temporal lobe and the decision-making prefrontal cortex, known to weaken with age. The team also noted that these participants reported improved sleep quality.
The scientific community has known about this amazing connection between scent and memory for quite some time. Loss of olfactory capacity can serve as a predictor for nearly 70 neurological and psychiatric diseases. These include Alzheimer’s, other dementias, Parkinson’s, schizophrenia, and alcoholism.
They have also observed that smell loss related to COVID could potentially lead to cognitive decline. Previous research demonstrated improved memory and language skills, and a decrease in depressive symptoms, amongst dementia patients exposed to a variety of odors twice daily over a period.
These findings inspired the UCI team to utilize this knowledge into creating an accessible, non-invasive tool for fighting dementia.
“The reality is that over the age of 60, the olfactory sense and cognition starts to fall off a cliff,” explained 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.”
“That’s why 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,” noted study first author Cynthia Woo.
“By making it possible for people to experience the odors while sleeping, we eliminated the need to set aside time for this during waking hours every day.”
The UCI findings affirmed the long-established connection between the olfactory system and memory. “The olfactory sense has the special privilege of being directly connected to the brain’s memory circuits,” explained study co-author Professor Michael Yassa.
“Everyone has experienced how powerful aromas are in evoking recollections, even from very long ago. 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.”
The UCI team is planning further investigation into the effects of this technique on individuals with diagnosed cognitive loss. They hope their findings will stimulate more research into olfactory therapies for memory impairment.
This fall, the team expects a product designed for home use and based on this study to hit the market. It will offer a novel, non-invasive approach to strengthen memory and possibly counter dementia.
Procter & Gamble provided financial support for the study. You can access the complete study in the journal Frontiers in Neuroscience.
Scent, or the ability to perceive odors, has a profound influence on our lives, even beyond memory enhancement. Olfaction, the sense of smell, is one of our five primary senses. It is a crucial component of our overall sensory experience.
Scent is closely linked to the emotional center of the brain, the amygdala, and the hippocampus, which is associated with memory and cognition. This is why particular scents can evoke strong emotions or memories, a phenomenon often referred to as the Proust Phenomenon, after the French writer Marcel Proust. He vividly described how the smell of a madeleine cake could transport him back to his childhood.
Scents can have a connection with behavior and mood. For example, lavender is often associated with relaxation and sleep, while citrus scents can promote alertness and energy. Retailers and marketers often use scent marketing, or “scent branding,” to enhance customer experience, drive brand recognition, or encourage certain behaviors such as spending more time in a store.
There’s a growing body of evidence suggesting that aromatherapy – the therapeutic use of essential oils extracted from plants – can aid in the relief of various ailments. For example, people often use eucalyptus oil to clear the respiratory tract or soothe physical discomfort.
Our sense of smell significantly influences our sense of taste. In fact, most of what we perceive as “taste” comes from our olfactory receptors. This is why when we have a cold or blocked nose, food can seem bland or tasteless.