The Sense of Small and Inhibition in Obesity (Smell_OB)

Investigating the Relationship Between the Sense of Smell and Cognitive Inhibition in Obesity: a Behavioural Experiment.

The aim of this research is to verify whether inhibitory control ability is different between a group of individuals with obesity and a group of individuals with normal weight in the presence of olfactory stimuli, different for valence, edibility (food versus no-food), and caloric density (high-calorie vs low-calorie content) of foods associated with odours.

Study Overview

• Status: Completed
• Conditions: Obesity
• Intervention / Treatment: Behavioral: Experimental Task

• Study Type: Observational
• Enrollment (Actual): 25

Contacts and Locations

Study Locations

• Italy
  • VCO
    • Piancavallo, VCO, Italy, 28824
      • IRCCS Istituto Auxologico Italiano - Ospedale San Giuseppe

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years to 55 years (Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Participants with obesity will be recruited at the beginning of a rehabilitative treatment at the Istituto Auxologico Italiano, IRCCS, San Giuseppe Hospital (Italy)

Description

Inclusion criteria:

• Right-handed
• diagnosis of obesity (i.e., the level of body mass index (BMI) higher or equal to 30).

Exclusion criteria:

• Concurrent neurological, neurodevelopmental (e.g., autism), motor, somatosensory and/or psychiatric disorders.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Cases; Right-handed Individuals diagnosed with obesity will be recruited at the beginning of a rehabilitative treatment at the Istituto Auxologico Italiano, IRCCS, San Giuseppe Hospital (Italy).	Behavioral: Experimental Task; The main task is an olfactory version of a traditional Go/No-Go task (Albayay et al., 2019): it includes the delivery of either an odour or clean air prior to the presentation of a visual target Moreover, all participants will be assessed with the italian version of the Stroop color and word test (Caffarra et al., 2004) to evaluate inhibition, together with selective and sustained attention. This neuropsychological test consists of three tables, showing color words (W), colored circles (C), and color words printed in incongruent ink (i.e., red printed in blue ink, CW), respectively. The Stroop effect consists of a delayed response when words have to be named according to the color of the ink, ignoring the meaning of the printed word.
Controls; Age-matched, right-handed, individuals with a healthy weight recruited outside the hospital through personal contacts of the researchers and word-of-mouth	Behavioral: Experimental Task; The main task is an olfactory version of a traditional Go/No-Go task (Albayay et al., 2019): it includes the delivery of either an odour or clean air prior to the presentation of a visual target Moreover, all participants will be assessed with the italian version of the Stroop color and word test (Caffarra et al., 2004) to evaluate inhibition, together with selective and sustained attention. This neuropsychological test consists of three tables, showing color words (W), colored circles (C), and color words printed in incongruent ink (i.e., red printed in blue ink, CW), respectively. The Stroop effect consists of a delayed response when words have to be named according to the color of the ink, ignoring the meaning of the printed word.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Error %	Percentage of the invalid answers, meaning when the participant erroneously press the key (i.e., answer) in the no-go (invalid) trials. This represents an index of inhibitory difficulty in the experimental task. This score will be computed according to Albayay and colleagues (2019).	baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Interference Error	It will computed according to the following formula: score = CW - ((W + C)/2). The lower is the score, the best is the performance. Notably for each condition (W, C, and CW) the number of error can range from O (no error) to 36 (maximun number of error). This computation derives from the seminal article for the Italian version of the test (Caffarra et al., 2004).	baseline

Collaborators and Investigators

• Sponsor: Istituto Auxologico Italiano
• Collaborators: Università degli Studi di Trento
• Investigators: Principal Investigator: Sofia Tagini, PhD, IRCCS Istituto Auxologico Italiano

Study record dates

Study Major Dates

• Study Start (Actual): January 10, 2023
• Primary Completion (Actual): June 30, 2024
• Study Completion (Actual): June 30, 2024

Study Registration Dates

• First Submitted: February 22, 2023
• First Submitted That Met QC Criteria: March 3, 2023
• First Posted (Actual): March 14, 2023

Study Record Updates

• Last Update Posted (Estimated): August 27, 2025
• Last Update Submitted That Met QC Criteria: August 20, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: obesity; food; cognitive inhibition; smell
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Nutrition Disorders; Overnutrition; Body Weight; Sensation Disorders; Overweight; Olfaction Disorders; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Anosmia; Obesity
• Other Study ID Numbers: 21C221

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No