Enjoy Your Favorite Scents and (Effortlessly) Reap the Benefits!

You might have said this of different tasks in your life, that you can “do it while sleeping”, meaning that you don’t have to use much conscious thought to do them.   Well, here’s a literally simple way to boost cognitive capacity and avoid dementia-related diseases: plug in an essential oil diffuser before you go to sleep!  

Previously, a 2009 study showed that olfactory enrichment (the daily exposure to multiple odorants) could improve both memory and neurogenesis (the formation of new neurons) in the mouse brain. In addition, novelty was the critical element in this kind of stimulation, as exposure to odorant mixtures did not produce these changes, while exposure to multiple odorants individually did.  

When some COVID-19 patients began to lose sense of smell, researchers tested subjects and found that MRI scans from individuals both pre-infection and post-infection have revealed neural deterioration that resembles a decade of aging in brain regions that receive olfactory-system projections.  Because olfactory loss precedes or accompanies cognitive decline in dementia-related diseases like Alzheimer’s and Parkinson’s diseases, researchers hypothesized that easy and affordable intervention to prevent cognitive decline could be using scents.

In a study, 20 participants (the Enriched Group) between ages 60 to 85 were given a diffuser and 7 essential oil odorants (rose, orange, eucalyptus, lemon, peppermint, rosemary, and lavender) in identical glass vials that each fit into the diffuser. They were asked to turn on the diffuser when they went to bed, and the odorant was released into the air during the night for 2 h when they first went to sleep. They rotated through the different odorants each night, continuing at home for 6 months. Twenty-three individuals in the control group also were provided with an odorant diffuser, and they followed the same regimen as the olfactory enrichment participants, however they were provided with bottles that contained distilled water with an undetectable amount of odorant added. 

The results showed a 226% difference between enriched and control older adults in performance on the Rey Auditory Verbal Learning Test (RAVLT). This test evaluates verbal learning and memory, including proactive interference, retroactive interference, delayed recall, retention, and recognition memory.  (Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults)

Before and after MRIs also showed that parts of the brain that receive input from the olfactory system, specifically the uncinate fasciculus, are modified by olfactory enrichment.  The researchers found a moderate increase in the mean diffusivity (MD) of the left uncinate fasciculus in the enriched group compared to controls, which correlates to increased integrity of that specific brain pathway.

What does this mean for the average senior?  Olfactory stimulation (smelling different scents) can be an important way to avoid dementia-causing diseases, and the cost of a programmable essential oil diffuser and a variety of different oils is not prohibitively expensive.  Here are a few options:

• GuruNanda Portable Diffuser 2.0, $40: We tested this diffuser and really liked the ease of use, reliability, and fact that you can use any brand of 10, 15 or 30ml scent bottle.  Although it doesn’t offer a 2 hour setting, it will auto-shutoff after 8 hrs. 

• Pura Smart Fragrance V3 Diffuser, $45: this diffuser holds 2 different scents, which you can control from your smartphone via an app.  It does require wifi and a smart phone to work, and doesn’t connect to 5G networks.

• GuruNanda Set of 8 Essential Oils (15ml x 8), $27, includes the most popular scents. 

• Laguna Moon Essential Oils Set, 12 pcs, $21, to add a bit more variety to your repertoire.

Best of all, this method is not hard to do; basically, with a little preparation, you can “do it while sleeping”!