Odor for Smell Perception

Overseen By Naelly Arriaga, MPH

Age: Any Age

Sex: Any

Trial Phase: Academic

Sponsor: Northwestern University

Disqualifiers: Smell or taste problems

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

Compensation: Varies

Number of Visits: Unknown

28 Participants Needed

Trial Summary

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications.

What data supports the effectiveness of the treatment Odor for smell perception?

The research suggests that using specific odors, like cinnamon, can help identify normal smell function, which might support the use of odors in treatments for smell perception issues. Additionally, a novel smell test using essential oils showed strong correlation with established smell tests, indicating that odors can be effectively used to assess and potentially improve smell perception. ^{1 2 3 4 5}

Is the treatment 'Odor' generally safe for humans?

The research suggests that odors can serve as a warning for potentially hazardous chemicals, indicating that they are generally safe when used as a detection tool. However, the perception of odors can vary widely among individuals, and some odors may have toxic potential that is not fully understood. ^{6 7 8 9 10}

How does the Odor treatment for smell perception differ from other treatments?

The Odor treatment is unique because it focuses on enhancing smell perception by leveraging the cognitive representation of odors, which is influenced by the individual's knowledge and identification of the odor source. This approach is different from other treatments that might not consider the psychological and cognitive aspects of odor perception. ^{11 12 13 14 15}

What is the purpose of this trial?

Investigating representations of odor intensity in human piriform cortex. To identify a neural representation of perceived odor intensity, it is necessary to dissociate stimulus concentration from perceived intensity. Experiments for this aim will measure human perceptual responses while manipulating intensity independently from concentration using two complementary approaches. In Experiment 1A, we will match perceived intensities across odors of different concentrations, allowing us to identify a neural representation of intensity that is independent of stimulus identity and concentration. In Experiment 1B, we will create conditions of different perceived intensity over constant odor stimuli using adaptation. Approaching the same question from different angles will strengthen the robustness of our findings. Preliminary data suggest that temporal features of the piriform neural response may represent odor intensity.

Research Team

christina zelano

Principal Investigator

Northwestern University

Eligibility Criteria

This study is for individuals who can perceive body odor. It aims to understand how the brain processes different intensities of odors, regardless of their concentration. Specific details about inclusion and exclusion criteria are not provided.

Exclusion Criteria

Screening for history of smell or taste problems

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Experiment 1A

Matching perceived intensities across odors of different concentrations to identify a neural representation of intensity independent of stimulus identity and concentration

15 minutes per session

Multiple sessions

Experiment 1B

Creating conditions of different perceived intensity over constant odor stimuli using adaptation

15 minutes per session

Multiple sessions

Follow-up

Participants are monitored for safety and effectiveness after experiments

4 weeks

Treatment Details

Interventions

• Odor

Trial Overview The trial is exploring how the human piriform cortex represents odor intensity by conducting two experiments: one matches perceived intensities across various concentrations, and another manipulates perceived intensity with constant stimuli using adaptation.

Participant Groups

Group I: Investigating representations of odor intensity in human piriform cortex. Experimental Treatment 1 Intervention

Odors will be presented at different concentrations.

Who Is Running the Clinical Trial?

Northwestern University

Lead Sponsor

Trials

1,674

Recruited

989,000+

Findings from Research

In a study of 272 participants, including healthy individuals and those with varying degrees of smell dysfunction, significant differences in chemical sensory functions were observed, particularly in patients with functional anosmia, who exhibited prolonged latency and reduced amplitude in olfactory and trigeminal event-related potentials (oERPs and tERPs).

The findings suggest that patients with functional anosmia also experience hypogeusia (reduced taste sensitivity), indicating a potential dysfunction of both olfactory and trigeminal nerves, which could be useful for clinical diagnosis and treatment strategies in affected populations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Examination of chemosensory functions in patients with dysosmia. Yang, L., Wei, Y., Zhang, W., et al.[2021]

A study involving 613 subjects found that identifying just one odor can effectively diagnose normal olfactory function (normosmia), simplifying clinical testing procedures.

Using a screening test with three specific odors (cinnamon, fish, and banana) achieved a sensitivity of 80.4% and specificity of 84.3%, allowing for reliable identification of normosmia and reducing the need for extensive olfactory assessments.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

How Many and Which Odor Identification Items Are Needed to Establish Normal Olfactory Function? Lötsch, J., Ultsch, A., Hummel, T.[2022]

The Affordable Rapid Olfaction Measurement Array (AROMA) is a novel, essential oil-based smell test that shows strong reliability and correlation with the established University of Pennsylvania Smell Identification Test (UPSIT), making it a promising tool for assessing olfactory function.

AROMA not only correlates well with UPSIT but also with sinonasal outcomes and perceived loss of smell, suggesting it could be particularly useful for evaluating olfactory dysfunction in patients with sinonasal disease.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Affordable Rapid Olfaction Measurement Array: A Novel, Essential Oil-Based Test Strongly Correlated with UPSIT and Subjective Outcome Measures. Villwock, JA., Li, J., Moore, C., et al.[2022]

The Parosmia Olfactory Dysfunction Outcomes Rating (DisODOR) is a newly developed and validated quality-of-life measure specifically for patients experiencing parosmia, demonstrating strong reliability and validity in a study involving 134 patients and 20 healthy controls.

DisODOR effectively distinguishes between patients with parosmia and healthy individuals, with a significant mean score difference of 45.0, and is sensitive to changes in patients' conditions, making it a useful tool for evaluating treatment outcomes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Development and Validation of the Parosmia Olfactory Dysfunction Outcomes Rating (DisODOR). Ioerger, P., Kallogjeri, D., Roland, L., et al.[2023]

Patients with persistent olfactory impairment reported significantly more difficulties in daily activities, with an average of 4.70 activities affected compared to only 0.61 in those who felt their sense of smell had improved.

Quality of life was notably lower in patients with ongoing smell issues, as only 50% reported overall life satisfaction compared to 87% in those who perceived their olfactory function as normal, highlighting the impact of smell on safety and eating habits.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Impact of olfactory impairment on quality of life and disability. Miwa, T., Furukawa, M., Tsukatani, T., et al.[2019]

Our sense of smell can detect an incredibly wide range of chemical compounds at very low levels, making it a crucial chemical sense that helps us interact with our environment.

Olfaction serves as a protective mechanism by alerting us to potentially harmful substances, while also being deeply connected to our emotions and memories, influencing our instinctive reactions to different odors.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[The power of odors--pathogenic or unpleasant]. Glück, U.[2016]

The paper provides a comprehensive review of odor thresholds for 214 potentially hazardous chemical vapors and gases, offering quantitative data crucial for industrial health and safety specialists.

It includes calculated safe dilution factors and odor safety factors for each compound, along with calibration charts to help estimate the detectability and warning potential of these chemicals, enhancing safety measures in environments where these substances are present.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Odor as an aid to chemical safety: odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Amoore, JE., Hautala, E.[2019]

About 40% of non-expert consumers in Pennsylvania cannot detect rotundone, a compound that gives a peppery flavor to some wines, indicating a specific anosmia for this compound in a North American population.

Detection thresholds for rotundone were similar whether assessed through orthonasal or retronasal methods, suggesting that future studies can focus on orthonasal assessments; however, added rotundone was generally disliked by participants, highlighting the need for winemakers to consider consumer preferences when producing peppery wines.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Individual Differences in Thresholds and Consumer Preferences for Rotundone Added to Red Wine. Gaby, JM., Bakke, AJ., Baker, AN., et al.[2021]

The study utilized a quantitative structure-activity relationship (QSAR) approach to analyze how different volatile organic compounds (VOCs) affect the senses of smell and nasal irritation, using data from 64 VOCs across various chemical series.

It was found that nasal pungency thresholds (NPTs) can effectively distinguish between selective and specific chemosensory effects in odor detection thresholds (ODTs), allowing for the prediction of ODTs based on NPTs for VOCs primarily influenced by selective effects.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A quantitative structure activity analysis on the relative sensitivity of the olfactory and the nasal trigeminal chemosensory systems. Abraham, MH., Sánchez-Moreno, R., Cometto-Muñiz, JE., et al.[2016]

In a study of 445 patients with olfactory testing, 76% had some level of olfactory impairment, with 30% experiencing complete anosmia, indicating a significant prevalence of smell disorders.

Patients with olfactory impairment were 37% more likely to encounter hazardous events related to their inability to smell, such as cooking incidents and undetected gas leaks, compared to only 19% of those with normal olfactory function, highlighting the safety risks associated with impaired smell.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Hazardous events associated with impaired olfactory function. Santos, DV., Reiter, ER., DiNardo, LJ., et al.[2022]

In a study with 76 participants evaluating 24 everyday odors, it was found that knowing the source of an odor significantly increased ratings of its intensity, pleasantness, and familiarity.

Participants rated odors highest when the names provided matched their own perceptions, indicating that cognitive understanding of odors influences how we perceive them.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Judgement of odor intensity is influenced by subjects' knowledge of the odor source. Distel, H., Hudson, R.[2019]

A review of 28 studies on odor perception revealed that the outcomes of these studies are heavily influenced by factors such as individual differences in perception, the characteristics of the odors tested, data collection methods, and analysis techniques.

Despite over 50 years of research, a universally accepted classification system for odor qualities remains elusive, indicating that current methodologies may need significant improvement to achieve unbiased results.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Odor classification: a review of factors influencing perception-based odor arrangements. Kaeppler, K., Mueller, F.[2016]

In a study involving 20 human subjects, it was found that people could distinguish between certain aromatic compounds better than others, particularly those containing methyl benzoate or phenyl methyl ketone, indicating that the type of functional group significantly affects odor discrimination.

The results suggest that functional oxygen-containing groups play a crucial role in how odorants interact with olfactory receptors, and that the structure of the alkyl group attached to these functional groups also influences odor quality, leading to poorer discrimination of aromatic compounds compared to aliphatic ones.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Olfactory discrimination ability for aromatic odorants as a function of oxygen moiety. Laska, M.[2019]

In a study involving 32 participants, researchers identified four distinct groups based on their sensitivity to 11 different musk odorants, revealing a range of olfactory detection thresholds.

Two specific groups of individuals exhibited heightened sensitivity to certain musk compounds, suggesting the existence of unique odor perception phenotypes (MSHM1 and MSHM2) that could have implications for understanding human olfactory diversity.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Odor perception phenotypes: multiple, specific hyperosmias to musks. Gilbert, AN., Kemp, SE.[2019]

The study successfully cloned and characterized the first human olfactory receptor (OR 17-40), which is crucial for understanding how humans perceive different smells.

Testing revealed that the receptor specifically responds to the odorant helional and one closely related compound, heliotropyl acetone, highlighting the receptor's selectivity and providing insights into the molecular mechanisms of olfactory perception.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cloning, functional expression and characterization of a human olfactory receptor. Hatt, H., Gisselmann, G., Wetzel, CH.[2016]

References

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

Examination of chemosensory functions in patients with dysosmia. [2021]

2. England pubmed.ncbi.nlm.nih.gov

How Many and Which Odor Identification Items Are Needed to Establish Normal Olfactory Function? [2022]

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

Affordable Rapid Olfaction Measurement Array: A Novel, Essential Oil-Based Test Strongly Correlated with UPSIT and Subjective Outcome Measures. [2022]

4. England pubmed.ncbi.nlm.nih.gov

Development and Validation of the Parosmia Olfactory Dysfunction Outcomes Rating (DisODOR). [2023]

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

Impact of olfactory impairment on quality of life and disability. [2019]

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

[The power of odors--pathogenic or unpleasant]. [2016]

7. England pubmed.ncbi.nlm.nih.gov

Odor as an aid to chemical safety: odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. [2019]

8. Switzerland pubmed.ncbi.nlm.nih.gov

Individual Differences in Thresholds and Consumer Preferences for Rotundone Added to Red Wine. [2021]

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

A quantitative structure activity analysis on the relative sensitivity of the olfactory and the nasal trigeminal chemosensory systems. [2016]

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

Hazardous events associated with impaired olfactory function. [2022]

11. England pubmed.ncbi.nlm.nih.gov

Judgement of odor intensity is influenced by subjects' knowledge of the odor source. [2019]

12. England pubmed.ncbi.nlm.nih.gov

Odor classification: a review of factors influencing perception-based odor arrangements. [2016]

13. England pubmed.ncbi.nlm.nih.gov

Olfactory discrimination ability for aromatic odorants as a function of oxygen moiety. [2019]

14. England pubmed.ncbi.nlm.nih.gov

Odor perception phenotypes: multiple, specific hyperosmias to musks. [2019]

15. France pubmed.ncbi.nlm.nih.gov

Cloning, functional expression and characterization of a human olfactory receptor. [2016]