The Effects of Smell on Mood and Physical Responses

National Center for Complementary and Integrative Health (NCCIH)56 enrolled

Overview

The purpose of this study is to examine the body's response to relaxing and stimulating fragrances commonly used in aromatherapy.

Despite aromatherapy's popularity, efficacy data are scant, and potential mechanisms are controversial. This randomized controlled trial examined the psychological, autonomic, endocrine, and immune consequences of one purported relaxant odor (lavender), one stimulant odor (lemon), and a no-odor control (water), before and after a stressor (cold pressor); 56 healthy men and women were exposed to each of the odors during three separate visits. To assess the effects of expectancies, participants randomized to the "blind" condition were given no information about the odors they would smell; "primed" individuals were told what odors they would smell during the session, and what changes to expect. Experimenters were blind. In each case we measured several different aspects of the cellular immune response, as well as skin barrier repair following tape stripping. This design allowed us to examine the ability of the odors to modulate endocrine and immune function, and health-relevant cutaneous responses.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Stress Anxiety Depression

Interventions

Exposure to relaxant and stimulant odorsBEHAVIORAL

A yellow-tinted cotton ball containing 100 ml of the essential oil or distilled water was taped between the nose and upper lip on top of a piece of surgical tape; use of the barrier tape avoided percutaneous absorption . This method provided continuous and uniform exposure across subjects that would not have been possible with ambient room inhalation, and helped maintain experimenter blindness.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 44 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Healthy adults with a normal sense of smell Exclusion Criteria: * Treatment with medication that has immunological or endocrinological consequences * Chronic health problems that affect immune or endocrine systems * Allergy to perfume or cosmetics * Problems with sense of smell * Respiratory problems * Smoker * Current active asthma * Use of psychoactive drugs or mood-altering medication * History of anxiety disorder, major depression, bipolar disorder, schizophrenia, or other psychotic disorders * History of chest pain or ventricular fibrillation

Locations (1)

Ohio State University Institute for Biobehavioral Medicine Research

Columbus, Ohio, United States

Outcomes

Primary Outcomes

Cortisol and Catecholamine Production

Cortisol, norepinephrine, epinephrine measured before and after physical (cold pressor) stressor, which occurred at 11:00.

Time frame: 3 Visits with at least 2 weeks between each. Average time to complete all visits was 64.46 days (SD 48.4). Cortisol: 9:05, 10:05, 10:55, 11:45, 12:15, 13:00. Nor/Epi: 9:05, 10:05, 10:55, 11:05, 11:45, 12:15

Immune Function

Stimulated Cytokine Production (Interleukin-6 (IL-6), Interleukin-10 (IL-10)) measured before and after cold pressor stressor, which occurred at 11:00.

Time frame: 3 Visits with at least 2 weeks between each. Average time to complete all visits was 64.46 days (SD 48.4). 9:05, 10:05, 11:45

Skin Barrier Repair

TEWL (Transepidermal Water Loss, via tape stripping procedure)measured before and after cold pressor stressor (11:00). After obtaining baseline measurements on volar forearm, cellophane tape(3M Scotch-type; St. Paul, MN) was applied repeatedly (6-50 times) to remove superficial layer of cornified skin cells. Tape stripping stopped when TEWL was elevated from the basal level of 5-7 g/h/m2 to at least 20 g/h/m2. The number of strips required to reach TEWL X20 g/m2/h was the measure of barrier. TEWL was measured with a computerized evaporimetry instrument, the DermaLabs (CyberDERM, Media, PA).

Time frame: 3 Visits with at least 2 weeks between each. Average time to complete all visits was 64.46 days (SD 48.4).10:05, 11:45, 13:15

Immune Function: Delayed Hypersensitivity to Candida(DTH)

DTH memory responses to a common infectious agent provided a measure of T-cell immunity. Nurses inoculated subject's arm with 0.1ml Candida (stock solution diluted 1:20 in saline, Greer Labs, NC) intradermally, after the cold pressor stressor. The wheal diameter (2 dimensions) was self-assessed at 24, 48, and 72 hours by participants given detailed instructions and templates for measurement.

Time frame: Day 1 11:45, Day 2 (24h) 11:45, Day 3 (48h) 11:45, Day 4 (72h) 11:45.

Data from ClinicalTrials.gov

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