A new study by neuroscientists at the University of California in the US found that when a pleasant fragrance was wafted through the bedrooms of older adults for two hours every night for six months, memories skyrocketed. Participants in the study were shown to achieve a two-hundred fold increase in their cognitive capacity compared to a control group.
The researchers said their study transforms previously known links between aroma and memory into an easy and affordable, non-invasive technique to strengthen memory and potentially curb dementia in the elderly.
The study involved men and women aged 60 to 85 without memory impairment. All were given a diffuser and seven cartridges, each containing a single and different natural oil. People in the enriched group received full-strength cartridges. 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.
People in the enriched group showed a 226 percent increase in cognitive performance compared to the control group, as measured by a word list test commonly used to evaluate memory. Imaging of the brain revealed better integrity in a brain pathway that connects the medial temporal lobe to the prefrontal cortex in the brain. The median temporal lobe is related to important cognitive and emotional functions in the brain, while the prefrontal cortex is largely associated with decision-making processes. Participants also reported sleeping more soundly
Scientists have long known that the loss of olfactory capacity, or ability to smell, can predict development of nearly 70 neurological and psychiatric diseases. These include Alzheimer’s and other dementias, Parkinson’s, schizophrenia and alcoholism. Evidence is emerging about a link between smell loss due to COVID and ensuing cognitive decrease.
Researchers have previously found that exposing people with moderate dementia to up to 40 different odors twice a day over a period of time boosted their memories and language skills, eased depression and improved their olfactory capacities. The new study aims to turn this knowledge into an easy and non-invasive dementia-fighting tool.
Over the age of 60, the olfactory sense and cognition starts to fall off sharply. The practicality of the new study arises from the fact that it is not realistic to expect an aged person suffering cognitive impairment to remember to open, take a whiff and close 40 deodorant bottles or more daily. This would be difficult even for those without dementia.
The researchers behind the new study said this is what prompted them to reduce the number of scents to just seven, and expose participants to just one scent daily, rather than the multiple aromas used simultaneously in previous research projects. By making it possible for people to experience the odors while sleeping, we also eliminated the need to set aside time for this during waking hours every day.”
The researchers say the results from their study bear out what scientists already know about the strong connection between smell and memory. Previous studies have established that 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, which is considered the relay station for all other motor and sensory impulses coming to the brain.
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 neuroscientists behind the research now plan on studying the impact of their technique on people with diagnosed cognitive loss. The team also hoped their finding would lead to more investigations into olfactory therapies for memory impairment.