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Olfactory training after COVID-19 illness

Treating post-COVID olfactory dysfunction with olfactory training

Several research studies on olfactory training have been published this year, due in part to one of the potential side effects of COVID-19 infection – loss of smell, or olfactory dysfunction. While research has not yet pinpointed the reason for this side effect, it is most frequently attributed to post-viral olfactory dysfunction (PVOD) or post-COVID olfactory dysfunction. One of the most effective treatments for PVOD is olfactory training, and Nexus Neurorecovery Center has been using structured, short-term exposure to selected essential oils to help restore patients’ sense of smell. The training has also been found to help regenerate damaged olfactory sensory neurons.

“Olfaction is critical for health, appetite, nutrition, and memory. It has been found to be important for memory due to the primary olfactory area comprising the entorhinal cortex which is a major input and output center of the hippocampus – the brain’s memory center,” explained Shannon Cosentino, Psy.D., Licensed Clinical Neurophyschologist at Nexus Neurorecovery Center.

Dr. Cosentino uses olfactory training to assess a patient’s sense of smell and identify which odarants they may be struggling with. From there, she develops a personalized treatment plan centered around the appropriate essential oil aromas and corresponding images that represent each smell.

“Olfactory training utilizes what is called the odor prism. It uses primary odors to retrain the nose, relying on memory and experience, to train those nerves to come back to life,” she explains. “Just as there are primary colors – red, blue, and yellow – there are thought to be primary smells, and each has a corresponding example that is typically used to represent it. Flowery – rose, fruity – lemon, aromatic – cloves, and resinous – eucalyptus.”

To begin olfactory training, patients place essential oil or a scent stick under the nose for five seconds while inhaling. They intentionally think about and try to remember what the corresponding image looks like. For example, they may place a rose-scented oil under their nose while inhaling and thinking about roses. They’ll move the oil or stick away and back again several times for a few minutes, then take a break for a few minutes before introducing the next scent.

Even if the person can’t yet smell the essential oil or scent stick, the nose and brain are working together to retrain neural connections.

“You want to identify the scent before you put it to your nose and mentally immerse yourself in the thought, picture the roses and what they smell like,” Dr. Cosentino said. “The idea is that you are combining the visual imagery with the stimulation of an isolated scent to retrain your nose on how to smell.”

The exercise should be repeated two to three times per day for six weeks, then a reassessment is done to note any improvements. A 2021 research study on the effectiveness of olfactory training for COVID-19 patients showed up to 90% of patients recovered from smell disorders when they began olfactory training within six weeks of the onset of symptoms. 

There is one additional element that Dr. Cosentino recommends to her patients: listening to music.

“Research has shown that perception of a smell is increased when presented together with a sound; as noted in spikes in activity at the olfactory tubercle, an area of the brain where smell is processed. Therefore, it is highly recommended individuals listen to music while engaging in olfactory training to further enhance effectiveness,” she said. 

To learn more about Nexus Neurorecovery Center and its programs, click here.

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