The Sense of Small and Inhibition in Obesity

Study Overview
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Brief Summary
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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.

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

Conditions
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Obesity

Intervention / Treatment
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* Behavioral: Experimental Task


Participation Criteria
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Eligibility Criteria
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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.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cases<br>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<br>* 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.<br>|
| Controls<br>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<br>* 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.<br>|

What is the study measuring?
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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 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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obesity, smell, food, cognitive inhibition