Episode 164: Michael Leon on olfactory stimulation as a buffer for dementia symptoms

// Feb 21, 2024

What if the path to delaying the onset of dementia symptoms begins at the nose?

It is a doorway that the research of Dr. Michael Leon opened with a 2023 study on the power of olfaction enrichment to influence memory function and brain health. The findings drew wide acclaim and interest when his results found that stimulation of our sense of smell with essential oils had a profound impact on memory, cognition, and language recall.

Our conversation with Leon on STEM-Talk Episode 164 is available now wherever you enjoy podcasts.

Leon’s long research career has focused on the influence of environmental enrichment on neurological function, disease, and disorders. He has studied the benefits of sensory-motor stimulation for children with autism spectrum disorder, for the treatment of anorexia and for those with dementia and neurological conditions.

He is a professor emeritus in the Department of Neurobiology and Behavior at the University of California Irvine, where his Leon Lab has focused on studying the benefits of increased sensory-motor activity in children with autism spectrum disorder.

The work that the Leon Lab is doing is fascinating, and the applications this olfaction stimulation study are potentially important and wide-reaching.


[00:02:33] Dawn starts the interview by asking Michael how he got interested in science.

[00:003:59] Dawn asks how Michael got involved in studying olfaction.

[00:04:36] Dawn asks about Michael’s research on Autism Spectrum Disorder (ASD), which resulted in a series of studies from 2013, 2015, and 2016.

[00:08:11] Dawn asks how Michael took the principles of environmental enrichment from his work on autism and applied them to his aging research, which began in 2018.

[00:09:28] Ken asks Michael about his 2023 study titled “Olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults.”

[00:11:25] Ken asks Michael why he chose the specific seven odors that he used in the study.

[00:12:24] Ken poses a listener question about whether or not a CPAP machine, which many older Americans use, would complicate Michael’s olfactory enrichment protocol, or if it is possible that the CPAP machine and the protocol can be used together.

[00:13:35] Dawn asks Michael what the selection and recruitment process was like for this study.

[00:14:48] Ken asks, in light of Michael’s research on the connection between memory and olfaction, what the potential consequences might be for people who reported loss or diminishing sense of smell following a COVID-19 infection.

[00:16:51] Ken asks if any of the olfactory remediation kits have shown promise in restoring lost olfaction following COVID-19.

[00:17:32] Ken asks what the mechanism is behind the loss of olfaction following menopause.

[00:19:43] Dawn asks Michael how his olfactory enrichment as a memory intervention compares to other memory interventions like dancing, music and audio books.

[00:20:22] Ken asks Michael what the limitations of the study were, as well as what kind of follow up he is planning.

[00:23:14] Ken asks if there is any promise in applying Michael’s olfactory therapy to mild TBI.

[00:24:10] Dawn asks Michael to describe how the brain processes information while asleep versus while awake, and if this influenced his study.

[00:25:53] Dawn mentions that the participants of Michael’s 2023 study were healthy, with no signs of dementia. She then asks Michael if he can speak to the potential use of olfactory enrichment for adults living with a dementia diagnosis.

[00:26:41] Ken asks if this olfactory enrichment approach is efficacious for Alzheimer’s and other forms of dementia.

[00:27:10] Ken mentions the difficulty in treating Alzheimer’s pharmacologically due to the varied causes of the disease among individuals.

[00:29:10] Ken asks Michael if there are environmental protocols other than olfactory enrichment that seem promising for preventing age-related memory decline.

[00:30:22] Ken mentions that while Michael’s olfactory enrichment does not cure dementia, it can slow its progression and even prevent symptoms from being expressed. Ken goes on to say that Michael’s paper had a hugely positive reaction.

[00:31:24] Ken asks about Michael’s plans to develop a CPAP and BIPAP version of his Memory Air device.

[00:32:21] Ken mentions that the positive response to Michael’s paper is probably because it is an effective approach that does not ask a lot of the person using it.

[00:33:24] Dawn asks if Michael thinks that the common notion that olfaction is the least important sense is misguided.

[00:34:18] Dawn asks Michael what is next for him and his team.

Study links:

Environmental Enrichment as an Effective Treatment for Autism, 2013, Behavioral Neuroscience,

Environmental Enrichment as a Therapy for Autism: clinical trial replication and extension, 2015, Behavioral Neuroscience.

Environmental Enrichment Therapy for Autism: Outcomes with Increased Access, 2016, Neural Plasticity,

Environmental Enrichment and Successful Aging, 2018, Frontiers in Behavioral Neuroscience,

Olfactory loss is a predisposing factor for depression, while olfactory enrichment is an effective treatment for depression, 2022, Frontiers in Neuroscience.

Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults, 2023, Frontiers in Neuroscience.


Michael Leon bio

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