Neuronal and Behavioral Effects of Implicit Priming in Obese Individuals

Not Applicable

Completed

• Conditions: Feeding Behavior; Overweight; Obesity
• Interventions: Behavioral: Control Implicit Priming; Behavioral: Active Implicit Priming

• Registration Number: NCT02347527
• Lead Sponsor: University of Colorado, Denver

Brief Summary

The overall goals of this project are to determine the impact of an implicit priming intervention, designed to alter food perceptions, on both brain responses to food and on food intake behaviors in overweight/obese individuals. The investigators hypothesized that this bottom-up sensory-level conditioning approach would effectively result in reduced preference for high-calorie foods.

Detailed Description

One factor that may contribute to susceptibility to obesity is a high responsivity to high-calorie foods in terms of cognitive factors such as emotional associations, reward value or reinforcing properties of food. Many of these processes involve learned associations thought to develop via classical conditioning through repeated pairings with external stimuli, which can influence food preferences and intake. As such, improving our understanding of the neuronal mechanisms underlying these processes and attempting to modify them may be a useful strategy to promote weight loss and maintenance. Therefore, the proposed study aims to investigate the effects of altering food perception on neuronal responses and food intake behaviors by using implicit priming, in which positively or negatively valenced images are presented immediately prior to food images, but are not consciously perceived.

The project goals are to determine the impact of the implicit priming intervention on both brain responses to food cues and on food intake behaviors in overweight/obese individuals. Food image ratings were assessed before and after either (a) an active implicit priming intervention or (b) a control intervention. One group of participants (n = 47; "MRI sample") completed the intervention during an fMRI scan and completed a visual food cues task both before and after the intervention (during fMRI), to assess intervention-related change in neuronal responses to food cues. In this group, food intake measures were also taken following fMRI. In a separate group of participants (n = 45; "Behavioral-only sample"), the primary outcome measure was the change in food image ratings from pre- to post-intervention; fMRI and measures of food intake were not assessed in this group.

Study Timeline

• Study Start: 2013-05
• Study First Submitted: 2015-01-16
• Study First Submitted QC: 2015-01-26
• Study First Posted: 2015-01-27
• Primary Completion: 2019-08
• Study Completion: 2019-08
• Status Verified: 2022-08
• Results First Submitted: 2022-08-11
• Results First Submitted QC: 2022-08-11
• Last Update Submitted: 2022-08-11
• Results First Posted: 2022-09-07
• Last Update Posted: 2022-09-07

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 92

Inclusion Criteria

• Overweight/obese adults
• Healthy weight adults

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Exclusion Criteria

• Vegetarian, vegan, or having other wide-ranging food restrictions
• Currently dieting
• MRI exclusion criteria, if in MRI sample (e.g., claustrophobia, metal in the body)

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Control Implicit Priming (MRI sample)	Control Implicit Priming	Participants will complete a control implicit priming intervention, which matches the active intervention, but with neutral stimuli as primes. In addition to measures of food image ratings, this group completed a visual food cues scan during fMRI to assess change in neuronal response to food cues. They also completed a measure of food intake post-intervention.
Active Implicit Priming (MRI sample)	Active Implicit Priming	Participants will complete active implicit priming, in which food images are implicitly primed (i.e., below conscious awareness) with images of positive or negative affect. In addition to measures of food image ratings, this group completed a visual food cues scan during fMRI to assess change in neuronal response to food cues. They also completed a measure of food intake post-intervention.
Active Implicit Priming (Behavioral-only sample)	Active Implicit Priming	Participants will complete active implicit priming, in which food images are implicitly primed (i.e., below conscious awareness) with images of positive or negative affect.
Control Implicit Priming (Behavioral-only sample)	Control Implicit Priming	Participants will complete a control implicit priming intervention, which matches the active intervention, but with neutral stimuli as primes.

Primary Outcome Measures

Name	Time	Method
Change in Food Image Ratings	Baseline to within 10 minutes post-intervention	Food image ratings (high-calorie foods) change from baseline, measured within 10 minutes post-intervention. Food images are rated on "desire to eat" by visual analogue scale (0-100; higher scores mean greater desire to eat). Negative values indicate reduced scores post-intervention compared to baseline, with greater numbers indicating greater reduction.
Neuronal Response to Food Cues	Baseline to post-intervention	Neuronal response while viewing visual food cues will be measured using functional magnetic resonance imaging (fMRI). Primary outcome was insula response change from baseline, as measured within 20 minutes after the intervention. A bilateral region of interest (ROI) for the insula was defined anatomically, with mean difference from baseline to post-intervention (% BOLD signal change) calculated across all voxels for that ROI. A positive number indicates a reduced response (with higher numbers indicating greater change) and a negative number indicates an increased response.

Secondary Outcome Measures

Name	Time	Method
Food Intake	1 hour post-intervention	Food intake during ad-lib lunch (kcals)

Trial Locations

Locations (1)

University of Colorado Anschutz Medical Campus; 🇺🇸 Aurora, Colorado, United States