Experiments to Test How and Why the Sense of Smell Differs Between People

Genetic Basis of Specific Anosmias

The ability to smell varies greatly between different individuals. Some people are unable to detect an odor that most people can smell. It is not known what causes these individual differences. Humans have about 1000 genes for odorant receptors that bind and detect odor molecules. It has been shown that some of these genes exist in two forms: a functional one and one that has been mutated and is therefore no longer functional. We think that people who can not smell a specific odor may carry the non-functional form of the gene for the receptor that detects the odor molecule. To test this hypothesis we want to find people who can not detect a specific smell and then compare their odorant receptor genes with those of people who can smell the odor.

Study Overview

• Status: Completed
• Conditions: Specific Anosmias
• Intervention / Treatment: Behavioral: smell tests

Detailed Description

The enjoyment of a fine wine, the odor of a ripe cheese, the memory of a long-lost grandmother brought back by the scent of her perfume, or the alarm we feel when we smell smoke are all produced by a functioning olfactory system. Interestingly, there are enormous individual differences in how we interpret these smells. Given almost any odor, some people will find it pleasant, others unpleasant. Ripe cheese or garlic may smell delicious to some, but repulsive to others. The scientific basis of this variation has not been well-studied. Despite the clear evidence for culture-based preferences for food and aromas, the nature-versus-nurture debate for smell remains unresolved. We believe there may be a genetic basis for our unique senses of smell. For example, some of us can smell methanethiol, the metabolite that is excreted in our urine after eating asparagus, whereas other people cannot. The Rockefeller University Smell Study seeks to recruit 400 normal subjects to track down the genetic basis of how we perceive smells. The study consists of up to two visits, each lasting up to 4 hours, in which we will test your perception of a variety of smells. On your first visit there will be a small blood sample taken (8.5 millileters) and your height and weight will be measured. If you are a woman of child-bearing age, we will ask you to provide a urine sample to test for pregnancy. If you are pregnant, you will not be permitted to participate in our study. You will fill out a short survey that asks some questions about yourself, your household, your personal habits, and your sense of smell. You will perform three different types of smell tests. In the first, you will be given two vials at a time and asked to tell us which contains an odor. In the second type of test, you will be asked to describe carefully your impression of three different odors. In the third type of test, you will be asked to rate odors according to their strength and pleasantness. All odorants will be presented to you in glass jars. You will be asked to smell odors in several hundred jars.

• Study Type: Observational
• Enrollment (Actual): 500

Contacts and Locations

Study Locations

• United States
  • New York
    • New York, New York, United States, 10021
      • Rockefeller University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

700 healthy normal volunteers will be recruited from the New York City area

Description

Inclusion Criteria:

18 years or older,

Male and Female

Normal sense of smell

-

Exclusion Criteria:

Not pregnant

No history of nasal illness or surgery

No seasonal allergies-

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Normal; 700 healthy adult volunteers will be drawn from the New York City area	Behavioral: smell tests; subjects are instructed to sniff two vials, one containing the solvent, the other a dilution of the odorant. They are asked to scan the vial with the stronger odor.

Collaborators and Investigators

• Sponsor: Rockefeller University
• Investigators: Principal Investigator: Leslie B. Vosshall, PHD, Rockefeller University

Study record dates

Study Major Dates

• Study Start: May 1, 2004
• Primary Completion (Actual): January 1, 2007
• Study Completion (Actual): May 1, 2010

Study Registration Dates

• First Submitted: September 21, 2005
• First Submitted That Met QC Criteria: September 21, 2005
• First Posted (Estimate): September 22, 2005

Study Record Updates

• Last Update Posted (Estimate): January 11, 2012
• Last Update Submitted That Met QC Criteria: January 10, 2012
• Last Verified: January 1, 2012

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nervous System Diseases; Neurologic Manifestations; Sensation Disorders; Olfaction Disorders; Anosmia
• Other Study ID Numbers: LVO-0539