The Effect of Odors on Asthma Symptoms

The Effect of Suggestion of Harmful/Beneficial Effects of Odors on Asthma Symptoms

An extended replication of Jaen & Dalton (2014), the investigators aim to investigate the role of odors and associated trigger beliefs on symptom perception and airway inflammation in individuals with asthma

Study Overview

• Status: Enrolling by invitation
• Conditions: Asthma
• Intervention / Treatment: Behavioral: Therapeutic Suggestion; Other: Phenylethyl Alcohol odor; Behavioral: Asthmogenic Suggestion

Detailed Description

Participants with asthma are randomly assigned to a 15-min (phenylethyl alcohol) odor inhalation, accompanied by either an asthmogenic suggestion (nocebo), or a therapeutic suggestion (placebo). Airway inflammation, lung function, and asthma symptoms are measured in response to the odor/suggestion, up to 24 hours after odor inhalation. The investigators are also measuring worry and heart rate variability as potential mediators of the response.

• Study Type: Interventional
• Enrollment (Estimated): 48
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Belgium
  • Leuven, Belgium, 3000
    • UZ Leuven

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• A physician diagnosis of asthma

Exclusion Criteria:

• FEV1 lower than 60% predicted
• clinical condition other than asthma

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Odor+ Positive belief; Participants receive 15 minute odor presentation (Phenylethyl Alcohol odor) accompanied by the suggestion that this odor improves asthma symptoms (therapeutic suggestion)	Behavioral: Therapeutic Suggestion; suggestions about potential beneficial effects of the odor are given; Other Names: placebo suggestion; positive treatment belief induction; Other: Phenylethyl Alcohol odor; Over the course of 15 minutes, participants, receive 15 short sniffs of Phenylethyl Alcohol odor
Experimental: Odor + Negative belief; Participants receive 15 minute odor presentation (Phenylethyl Alcohol odor) accompanied by the suggestion that this odor worsens asthma symptoms (asthmogenic suggestion)	Other: Phenylethyl Alcohol odor; Over the course of 15 minutes, participants, receive 15 short sniffs of Phenylethyl Alcohol odor; Behavioral: Asthmogenic Suggestion; suggestions about potential negative effects of the odor are given; Other Names: nocebo suggestion; negative treatment belief

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline Exhaled Nitric Oxide to 24 hours after odor induction	Fraction of exhaled nitric oxide	baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
asthma symptoms	measured using the Asthma Symptom Checklist	baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction
Forced Expiratory Volume at one second (FEV1)	Measured using Jaeger Masterscreen Spirometer, according to ERS-ATS guidelines	baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction
Worry	measured using worry Visual Analog Scales	baseline, immediately after odor induction, 2 hours after odor induction, 24 hours after odor induction
Cortisol	cortisol awakening response (AUC), and changes in cortisol (AUC) will be measured using saliva sampling	baseline, immediately after odor induction, 2 hours after odor induction, at awakening, 30 min after awakening, 24 hours after odor induction
Change in Heart rate and Heart Rate Variability (HRV)	24 hour heart rate data will be recorded using an ambulatory ECG monitor, and analyzed in 1 hour epochs, extracting mean of successive differences (MSD) as a variable of interest.	change from baseline to 24 hours after odor induction
Change in Respiratory rate	respiratory rate (breaths/min) is recorded continuously, and changes between baseline and odor presentation periods will be analysed	change from baseline to 15 min odor presentation
change in Fraction of end-tidal carbon dioxide (FetCO2)	FetCO2 (plateau %CO2 in exhaled air) is recorded continuously, and changes between baseline and odor presentation periods will be analysed	change from baseline to 15 min odor presentation

Collaborators and Investigators

• Sponsor: Universitaire Ziekenhuizen KU Leuven
• Collaborators: KU Leuven; Research Foundation Flanders
• Investigators: Principal Investigator: Thomas Janssens, PhD, KU Leuven

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2015
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: December 1, 2015
• First Submitted That Met QC Criteria: December 7, 2015
• First Posted (Estimated): December 8, 2015

Study Record Updates

• Last Update Posted (Actual): July 3, 2024
• Last Update Submitted That Met QC Criteria: July 2, 2024
• Last Verified: July 1, 2024

More Information

Terms related to this study

• Keywords: inflammation; Odor; trigger; nocebo
• Additional Relevant MeSH Terms: Respiratory Tract Diseases; Immune System Diseases; Lung Diseases; Hypersensitivity, Immediate; Bronchial Diseases; Lung Diseases, Obstructive; Respiratory Hypersensitivity; Hypersensitivity; Asthma; Anti-Infective Agents, Local; Anti-Infective Agents; Disinfectants; Phenylethyl Alcohol
• Other Study ID Numbers: S57940