Can You Smell Your Way To A Better Memory?

Why yes! And here's how.

Sometimes you hear about a study result and think, could that really be so?

Such as…

In a study published in July in the journal Frontiers of Neuroscience, researchers set out to determine the effect of “olfactory stimulation” (stimulating the sense of smell) on memory function. To do so, they had participants sleep with an essential oil diffuser at their bedside for 6 months. What did they find?

Compared to controls, subjects in the aromatherapy group demonstrated a statistically significant 226% improvement on a test of working memory.

Skeptical? I don’t blame you.

Could having pleasant aromas wafting through the air while you sleep really enhance your memory. Moreover, could it even protect against dementia and maybe even birth new brain cells?

Readers of this newsletter or listeners of The Better Brain Fitness podcast may be a bit more credulous. As I’ve indicated before, I think there is strong evidence that the driving factor in cognitive decline and dementia is the reduction in cognitive stimulation over the typical human life.

And one way in which cognitive stimulation can decline is via an impairment in one of our primary senses. The lower the resolution of the sensory input from our eyes, ears, mouth, skin, joints, or nose, the less information our brain has to process. Notably, sensory impairment in every one of our senses has been shown to be associated with a heightened risk of cognitive decline and dementia.

I’ve also talked at length about the importance of whole-brain cognitive stimulation in preventing age-related cognitive decline. But does smelling stuff really qualify?

Olfaction is certainly not a whole brain activity. Compared to other animals, humans aren’t especially good smellers. And that’s reflected in the fact that we don’t devote a whole lot of cortical real estate to olfaction. Many more neurons are dedicated to processing vision, hearing and touch than smell and taste.

But olfaction does have something unique going for it, which is that the part of the cortex that processes smells (“entorhinal cortex”) is next door to the hippocampus, the part of our brain that’s crucial for long term memory formation (and that’s involved early on in Alzheimer’s.) This territorial proximity is often invoked to explain the tight link between smells and memory. 

So, yes, it is biologically plausible that olfactory stimulation could boost memory.

Furthermore, a number of empirical findings strengthen the case, which are outlined in the above-referenced article. These include: 

• “Olfactory Enrichment” improves brain and behavior in animals. Olfactory enrichment of a mouse’s environment improves memory and leads to the birth of new brain cells.

• Olfactory stimulation restores olfactory function in humans. Brains are plastic. Including the parts of our brain that register the heady aroma of fresh-baked bread or the stink of a dead skunk. Stimulating our sense of smell has been shown to help restore loss of smell in humans.

• Brains get bigger with olfactory enrichment. The restoration of function that occurs with olfactory stimulation also leads to an increase in gray matter in the thalamus and hippocampus.

• Olfactory enrichment improves cognitive function in dementia. Exposing older adults with moderate dementia to 40 odorants twice a day for 15 days led to marked improvements in memory, attentions, verbal fluidity, and language skills.

In sum, it is indeed both biologically plausible and empirically supported that olfactory stimulation could boost cognitive function, promote neuroplasticity, and protect against dementia. And while the initial study I mentioned definitely has its limitations - including a small sample size - the overall signal here is strong enough to take notice.

Plus, it’s the best kind of intervention - enjoyable with virtually no downsides, and a potentially large upside.

To smell your way to a better memory, here’s how to replicate the protocol in the study.

First, gather the following supplies:

1. An essential oil diffuser

2. 7 different essential oils.

3. A bed (optional).

With your supplies acquired, run your diffuser for at least 2 hours each night. Use a different oil each night, rotating through all 7 scents each week.

Now, the study ran for 6 months, but there’s no reason to stop there. However, given that novelty is a critical factor in the brain boosting effects of olfactory stimulation, I think it’d be wise to rotate out the set of oils after 6 months. Fortunately, the world of aromas is vast.

All in all, the crucial feature is that you’re consistently exposing your olfactory regions to novel and noticeable smells for a sustained period of time. If you recall, novelty was also the feature in music that is most stimulating, which is no coincidence. It’s new stimuli that leads to brain change, and stimulating brain change is essential for keeping our brain healthy and fit (in case you missed it, here is the episode on “What kind of music stimulates the brain the most?”)

Brain-Enhancing Technology Recommendation: The Essential Oil Diffuser

If find yourself in need of a brain-enhancing aromatherapy device, this is one that’s worked well for my wife Jenny and I.

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If you have a question for the Better Brain Fitness podcast, click here to submit it.

That’s it for this issue of The Brainjo Connection. Have a wonderful week, and a Happy Labor Day!

Josh