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The Sweet Smell of Better Brain Function

Last month I mentioned an interesting thing about music… how certain songs can transport you back in time to a specific moment that evokes a cherished memory.

Have you ever noticed that the same thing happens with certain scents and odors? It might be a whiff of perfume that suddenly brings an image of your mother; or maybe freshly mowed grass that produces the youthful memory of hot summer days spent outdoors playing with friends.

There are a lot of memories, emotions and feelings associated with our sense of smell. So it’s probably not surprising that people who have a poor sense of smell also tend to have worse memories.

As a matter of fact, an inability to identify common odors is often associated with greater likelihood of developing cognitive problems over the next five years.

Study after study shows that folks who have the worst ability to detect the odors have reduced volume of the hippocampus. This part of the brain plays an important role in consolidating short-term memories into long-term memories.

They also have a greater burden of amyloid plaque. Plus, their entorhinal cortex – which plays a role in memory formation and consolidation – tends to be thinner.

Over the years, I’ve often used Smell Identification Testing in my own practice. It’s a collection of different scents, including odors such as coffee, peanut butter, lemon, lavender, peppermint and others.

When a patient couldn’t identify them, I immediately knew that I would need to keep a close watch on that patient for cognitive issues over the upcoming years. Also for Parkinson’s disease, especially if they had a history of chronic constipation.

Now, we are discovering that there is another side of the coin.

Scents Produce a Dramatic Boost in Memory and Cognition

A study out of the University of California revealed that when older adults use fragrance diffusers in their bedrooms at night, their cognitive performance improves.

The research team split a group of seniors between the ages of 60 and 85 years of age into two groups. None of the participants had a diagnosis of cognitive impairment or dementia.

The first group received diffusers that were fully scented with essential oils. The second group received diffusers with just a trace of scent.

For six months all of the individuals were exposed to seven different scents each week; one odor per night for a period of two hours. The fragrances included rose, orange, eucalyptus, lemon, peppermint, rosemary and lavender.

Well, the results were absolutely amazing… just amazing!

The people who used the full-scented diffusers for six months performed 226% better on memory tests compared to those who used the ones with only trace amounts of scent. Not only did they have improved cognition, they also had better neural functioning.

And here’s the best part!

Strengthen Memory Pathways in Your Brain

It turns out that the full-scent group showed improved integrity of a specific limbic pathway (the sense of smell projects directly to the limbic system and triggers emotional responses). It’s called the left uncinate fasciculus, and it plays a crucial role in learning and memory.

This pathway deteriorates as we age; more so in Alzheimer’s disease.

This suggests that, in addition to helping improve our memories, regularly exposing ourselves to a variety of scents may actually strengthen brain functions that are protective against Alzheimer’s.

Personally, I have fragrance in my house all of the time, and change scents regularly. But if you only want to use it for two hours a night like they did in the study, it should do your brain a world of good.

In the meantime, take time to notice all of the odors around you… the smell of freshly minced curcumin… the scent of freshly cut grass… the salty odor of the ocean… the sweet smell of roses…

You might just strengthen your brainpower at the same time, without even realizing it!


Growdon ME, Schultz AP, Dagley AS, Amariglio RE, Hedden T, Rentz DM, Johnson KA, Sperling RA, Albers MW, Marshall GA. Odor identification and Alzheimer disease biomarkers in clinically normal elderly. Neurology. 2015 May 26;84(21):2153-60.

Kreisl WC, Jin P, Lee S, Dayan ER, Vallabhajosula S, Pelton G, Luchsinger JA, Pradhaban G, Devanand DP. Odor Identification Ability Predicts PET Amyloid Status and Memory Decline in Older Adults. J Alzheimers Dis. 2018;62(4):1759-1766.

Woo CC, Miranda B, Sathishkumar M, Dehkordi-Vakil F, Yassa MA, Leon M. Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults. Front Neurosci. 2023 Jul 24;17:1200448.