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

250 Participants Needed

Trial Summary

What is the purpose of this trial?

To date, there is no validated pharmacotherapy for olfactory disorders. Interestingly, olfactory training - the intentional exposure to odorants for the purposes of retraining the sense of smell - has shown success with as many as 28% of subjects over the course of 12 weeks.

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 data supports the effectiveness of the treatment Olfactory Training for Loss of Smell?

Research shows that olfactory training, which involves regularly smelling a set of odors, can help improve the sense of smell in people with olfactory loss. Studies have found it effective for various causes of smell dysfunction, including after infections and injuries, and it may also support cognitive functions and emotional well-being. ^{1 2 3 4 5}

Is olfactory training safe for humans?

Olfactory training has been studied in humans for improving smell function, and there is no specific safety concern reported in the studies available. It is generally considered safe for use in humans. ^{3 6 7 8 9}

How does olfactory training differ from other treatments for loss of smell?

Olfactory training is unique because it involves regularly smelling specific odors to improve the sense of smell, unlike other treatments that might not focus on sensory exposure. This method is non-invasive and can enhance olfactory function by increasing sensitivity to odors and potentially improving overall smell ability. ^{1 3 4 10 11}

Research Team

Jennifer A Villwock, MD

Principal Investigator

University of Kansas Medical Center

Eligibility Criteria

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

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

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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]

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]

References

1. United States pubmed.ncbi.nlm.nih.gov

Olfactory training - Thirteen years of research reviewed. [2022]

2. Germany pubmed.ncbi.nlm.nih.gov

Effect of olfactory bulb atrophy on the success of olfactory training. [2022]

3. Netherlands pubmed.ncbi.nlm.nih.gov

Factors associated with relevant olfactory recovery after olfactory training: a retrospective study including 601 participants. [2021]

4. United States pubmed.ncbi.nlm.nih.gov

The effect of olfactory training on the odor threshold in patients with traumatic anosmia. [2018]

5. United States pubmed.ncbi.nlm.nih.gov

Parosmia is Associated with Relevant Olfactory Recovery After Olfactory Training. [2021]

6. Switzerland pubmed.ncbi.nlm.nih.gov

Drug-Associated Parosmia: New Perspectives from the WHO Safety Database. [2022]

7. United States pubmed.ncbi.nlm.nih.gov

Olfaction and olfactory epithelium in mice treated with zinc gluconate. [2012]

8. China pubmed.ncbi.nlm.nih.gov

[Efficacy and associated factors of olfactory training in the treatment of olfactory dysfunction]. [2019]

9. England pubmed.ncbi.nlm.nih.gov

Decongestant use and the risk of myocardial infarction and stroke: a case-crossover study. [2023]

10. United States pubmed.ncbi.nlm.nih.gov

Effects of olfactory training in patients with olfactory loss. [2022]

11. Netherlands pubmed.ncbi.nlm.nih.gov

The effect of olfactory training on olfactory bulb volumes in patients with idiopathic olfactory loss. [2020]