Olfactory Training for Loss of Smell

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Kansas Medical Center

Disqualifiers: Pregnancy, Dementia, Parkinson's, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: Unknown

Duration: 12 weeks

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to explore the effectiveness of olfactory training for individuals who have lost their sense of smell. Participants will smell either 4 or 14 different scents twice a day to determine if this improves their ability to smell. The trial seeks individuals who have difficulty smelling and can commit to this daily routine. As an unphased trial, it offers participants the opportunity to contribute to groundbreaking research in olfactory recovery.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. It might be best to discuss this with the trial coordinators.

What prior data suggests that olfactory training is safe for humans?

Research has shown that olfactory training, which involves intentionally smelling different scents, is generally easy for people to handle. Studies on individuals who lost their sense of smell due to COVID-19 have found that many experienced improvements without serious side effects.

Participants typically smell a set number of scents twice a day. In one study, almost 60% of participants noticed a significant improvement in their sense of smell after completing the training. While this method may not work for everyone, it is considered safe since no severe side effects have been reported.

Overall, evidence suggests that olfactory training is a low-risk treatment worth considering for those wanting to regain their sense of smell. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about olfactory training for loss of smell because it offers a non-invasive, simple method that aims to naturally enhance the brain’s ability to recognize and process scents. Unlike medications or surgeries that are typical standard treatments, this approach leverages the brain's plasticity by using controlled scent exposure. By comparing different numbers of scents—four versus fourteen—researchers hope to understand how varied scent exposure impacts recovery, potentially leading to personalized therapy strategies. This method could revolutionize treatment for smell loss by tapping into the brain's ability to heal and adapt, offering a promising alternative to traditional options.

What evidence suggests that olfactory training could be effective for loss of smell?

This trial will compare two different olfactory training methods for loss of smell. Research has shown that olfactory training, which involves regularly smelling certain scents to retrain the nose, can help some people with smell disorders. For example, one study found that 84.5% of participants regained their normal sense of smell after this training. Another study showed that olfactory training alone significantly helped people with long-term smell problems. However, not all studies agree; one found that 12 weeks of training did not help those who lost their sense of smell due to COVID-19. Overall, while results can vary, promising evidence suggests that olfactory training can improve the sense of smell for many people. In this trial, participants in Group A will inhale 4 different scents, while those in Group B will inhale 14 different scents, with both groups doing so twice a day. ^{2 3 6 7 8}

Who Is on the Research Team?

Jennifer A Villwock, MD

Principal Investigator

University of Kansas Medical Center

Are You a Good Fit for This Trial?

This trial is for individuals who have experienced a traumatic brain injury and can perform smell tests. It's not for those under 18 or over 80, pregnant women, people with poor compliance, those unable to do follow-ups, in other studies, or with conditions like dementia or certain sinonasal impacting diseases.

Inclusion Criteria

You have had a head injury in the past.

Ability to complete objective olfactory tests and comply with olfactory training protocol

Exclusion Criteria

You are allergic to any of the scents or ingredients used in our smell tests and training.

Patients with poor or questionable compliance, as participation requires daily compliance with study protocol

Patients unable to perform routine follow-up

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants undergo olfactory training by inhaling either 4 or 14 different scents twice a day

12 weeks

Follow-up

Participants are monitored for changes in olfactory threshold and identification, as well as neurocognition and tolerance

up to 6 months

What Are the Treatments Tested in This Trial?

Interventions

• Olfactory Training

Trial Overview The study is testing olfactory training - exposing participants to different smells regularly to try and improve their sense of smell after a brain injury. There's no drug involved; it's about retraining the nose.

How Is the Trial Designed?

Group I: Group A: 4 scents Experimental Treatment 1 Intervention

Participants will be asked to inhale 4 different scents 2 times a day.

Group II: Group B: 14 scents Active Control 1 Intervention

Participants will be asked to inhale 14 different scents 2 times a day.

Who Is Running the Clinical Trial?

University of Kansas Medical Center

Lead Sponsor

Trials

527

Recruited

181,000+

Published Research Related to This Trial

Olfactory training using phenyl ethyl alcohol (PEA) significantly improved odor detection thresholds in 10 out of 42 patients with traumatic anosmia, compared to only 2 out of 39 patients using mineral oil, indicating the efficacy of PEA in enhancing olfactory function.

The study suggests that olfactory training with PEA is a promising intervention for patients with anosmia following head injuries, although no significant changes were observed in olfactory bulb volume or overall smell identification scores between the two groups.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of olfactory training on the odor threshold in patients with traumatic anosmia. Jiang, RS., Twu, CW., Liang, KL.[2018]

Olfactory training (OT) may not only help improve the sense of smell in individuals with olfactory disorders but could also enhance psychological functioning, potentially benefiting cognitive and emotional processes due to the direct connection between the olfactory bulb and the limbic system.

The review highlights the need for more research on OT, including its molecular and neuroanatomical effects, to better understand its role in supporting cognitive functions and overall well-being.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Olfactory training - Thirteen years of research reviewed. Pieniak, M., Oleszkiewicz, A., Avaro, V., et al.[2022]

In a study of 153 patients with post-infectious olfactory dysfunction (PIOD) receiving olfactory training, the presence of parosmia was linked to significant improvements in olfactory discrimination and identification, especially in those with lower baseline olfactory function.

Older patients showed more significant improvements in odor threshold, suggesting that age may play a role in recovery outcomes for olfactory function after training.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Parosmia is Associated with Relevant Olfactory Recovery After Olfactory Training. Liu, DT., Sabha, M., Damm, M., et al.[2021]

Olfactory training over 16 weeks significantly improved olfactory function in patients with olfactory dysfunction, with an overall efficacy rate of 40% based on the Sniffin' Sticks olfactory test results.

Patients with less than a year of olfactory dysfunction showed even better improvement, with a 50.9% efficacy rate, indicating that earlier intervention may lead to more successful outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Efficacy and associated factors of olfactory training in the treatment of olfactory dysfunction]. Yan, XG., Gao, X., Sun, ZF., et al.[2019]

Olfactory loss affects about 20% of people and can lead to decreased enjoyment in activities like eating, drinking, and even sex, as well as contributing to depression.

Olfactory training (OT), which typically involves smelling four specific scents twice daily for 12 weeks, has been shown to effectively improve olfactory function in individuals with olfactory loss from various causes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of olfactory training on olfactory bulb volumes in patients with idiopathic olfactory loss. Mahmut, MK., Musch, M., Han, P., et al.[2020]

Citations

1. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/40202093/

Olfactory training for the treatment of COVID-19 related ... Overall, 84.5% achieved normosmia, with full recovery (FR) significantly higher in PB. At baseline, OT had lower olfactory scores and higher ...

2. clinicaltrials.gov clinicaltrials.gov/study/NCT07190911

Efficacy of Olfactive Training on Loss of Smell and Taste ... The purpose of this study is to evaluate efficiency of two months of olfactive training on olfactory and taste loss secondary to covid-19. We ...

3. frontiersin.org frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2024.1457527/full

The effectiveness of olfactory training for chronic ... Conclusions: In our assessment, olfactory training alone produces significant improvements in chronic olfactory dysfunctions. However, a ...

4. sciencedirect.com sciencedirect.com/science/article/pii/S1808869424000661

Therapeutic effects of olfactory training and systemic ... The olfactory training has significantly improved the smell alteration at the end of 3- and 12- months follow-up in A and B groups. Conclusion. A three-months ...

5. onlinelibrary.wiley.com onlinelibrary.wiley.com/doi/full/10.1002/lary.32275

Effect of Olfactory Training in COVID‐19 Related ... This study found that 12 weeks of classical olfactory training is not effective in the treatment of COVID-19 induced olfactory dysfunction.

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12302507/

The impact of olfactory loss on quality of life: a 2025 review With olfactory loss, food-related quality of life decreases. Eating becomes sustenance stripped of its joy. Patients with anosmia report ...

7. sciencedirect.com sciencedirect.com/science/article/pii/S2667268524000433

Losing olfaction in COVID-19: Screening, training and ... Olfactory performances improved significantly after training, irrespective of the training paradigm and 59% of patients displayed a clinically significant ...

8. bmjopen.bmj.com bmjopen.bmj.com/content/15/5/e094027

Protocol for olfactory training in persisting COVID-19 ... We designed a monocentric, single-blinded randomised controlled trial evaluating the efficacy of olfactory training (OT) in individuals with persisting COVID- ...