INHALING PLEASANT SCENTS DURING SLEEP TIED TO A DRAMATIC BOOST IN COGNITION

Inhaling a pleasant aroma during sleep has been linked to a “dramatic” improvement in memory, early research suggests.

In a small, randomized control trial researchers found that when cognitively normal individuals were exposed to the scent of an essential oil for 2 hours every night over 6 months, they experienced a 226% improvement in memory compared with a control group who received only a trace amount of the diffused scent.

In addition, functional magnetic resonance imaging (fMRI) showed that those in the enriched group had improved functioning of the left uncinate fasciculus, an area of the brain linked to memory and cognition, which typically declines with age.

“To my knowledge, that level of [memory] improvement is far greater than anything that has been reported for healthy older adults and we also found a critical memory pathway in their brains improved to a similar extent relative to unenriched older adults,” senior investigator Michael Leon, PhD, professor emeritus, University of California, Irvine, told Medscape Medical News. The study was published online July 24 in Frontiers of Neuroscience.

Olfactory enrichment “involves the daily exposure of individuals to multiple odorants” and has been shown in mouse models to improve memory and neurogenesis, the investigators note.

A previous study showed that exposure to individual essential oils for 30 minutes a day over 3 months induced neurogenesis in the olfactory bulb and the hippocampus.

“The olfactory system is the only sense that has a direct ‘superhighway’ input to the memory centers areas of the brain; all the other senses have to reach those brain areas through what you might call the ‘side streets’ of the brain, and so consequently, they have much less impact on maintaining the health of those memory centers.”

When olfaction is compromised, “the memory centers of the brain start to deteriorate and, conversely, when people are given olfactory enrichment, their memory areas become larger and more functional,” he added.

Olfactory dysfunction is the first symptom of Alzheimer’s disease (AD) and is also found in virtually all neurological and psychiatric disorders.

“I’ve counted 68 of them — including anorexia, anxiety, ADHD [attention-deficit/hyperactivity disorder], depression, epilepsy and stroke. In fact, by mid-life, your all-cause mortality can be predicted by your ability to smell things,” Leon said.

Leon and colleagues previously developed an effective treatment for autism using environmental enrichment that focused on odor stimulation, along with stimulating other senses. “We then considered the possibility that olfactory enrichment alone might improve brain function.”