Feeding Behavior, Obesity, Overweight
Conditions
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.
Interventions
BEHAVIORALActive Implicit Priming
A 10-minute implicit priming intervention, associating food images with images of positive or negative valence.
BEHAVIORALControl Implicit Priming
A 10-minute implicit priming intervention, associating food images with images of neutral valence.
Sponsors
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
University of Colorado, Denver
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Intervention model description
The MRI sample and Behavioral-only sample involve separate participants who complete the same intervention (assigned to either active or control groups), but the MRI sample also completed MRI outcomes and a food intake outcome that the Behavioral-only sample did not.
Eligibility
Sex/Gender
ALL
Age
21 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Overweight/obese adults * Healthy weight adults
Exclusion criteria
* Vegetarian, vegan, or having other wide-ranging food restrictions * Currently dieting * MRI
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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
| Measure | Time frame | Description |
|---|---|---|
| Food Intake | 1 hour post-intervention | Food intake during ad-lib lunch (kcals) |
Countries
United States
Participant flow
Recruitment details
For the Behavioral-Only sample, participants were recruited via flyer advertisement in Aurora, CO, between May 2013 and March 2014. For the MRI sample, participants were recruited via email and flyer advertisement in Aurora, CO, between May 2015 and August 2019.
Pre-assignment details
47 participants were in the MRI sample and 45 were in the Behavioral-only sample, for a total of 92 unique study participants.
Participants by arm
| Arm | Count |
|---|---|
| Active Implicit Priming (MRI Sample) Participants completed active implicit priming, in which food images were implicitly primed (i.e., below conscious awareness) with images of positive or negative affect. This group completed the intervention during fMRI scan.
Active Implicit Priming: A 10-minute implicit priming intervention, associating food images with images of positive or negative valence. | 22 |
| Control Implicit Priming (MRI Sample) Participants completed a control implicit priming intervention, which matched the active intervention, but with neutral stimuli as primes. This group completed the intervention during fMRI scan.
Control Implicit Priming: A 10-minute implicit priming intervention, associating food images with images of neutral valence. | 19 |
| Active Implicit Priming (Behavioral-only Sample) Participants completed active implicit priming, in which food images were implicitly primed (i.e., below conscious awareness) with images of positive or negative affect.
Active Implicit Priming: A 10-minute implicit priming intervention, associating food images with images of positive or negative valence. | 22 |
| Control Implicit Priming (Behavioral-only Sample) Participants completed a control implicit priming intervention, which matched the active intervention, but with neutral stimuli as primes.
Control Implicit Priming: A 10-minute implicit priming intervention, associating food images with images of neutral valence. | 20 |
| Total | 83 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 | FG002 | FG003 |
|---|---|---|---|---|---|
| Overall Study | Excluded from analyses due to excess movement during MRI scan | 1 | 1 | 0 | 0 |
| Overall Study | Excluded from analyses due to non-compliance with study procedures | 0 | 1 | 0 | 0 |
| Overall Study | Excluded from analyses due to technical difficulties during the study visit | 1 | 0 | 1 | 2 |
| Overall Study | MRI not completed due to technical difficulties | 1 | 0 | 0 | 0 |
| Overall Study | MRI stopped due to participant anxiety | 0 | 1 | 0 | 0 |
Baseline characteristics
| Characteristic | Control Implicit Priming (MRI Sample) | Active Implicit Priming (Behavioral-only Sample) | Active Implicit Priming (MRI Sample) | Control Implicit Priming (Behavioral-only Sample) | Total |
|---|---|---|---|---|---|
| Age, Continuous | 37.3 years STANDARD_DEVIATION 13.6 | 30.7 years STANDARD_DEVIATION 6 | 41.5 years STANDARD_DEVIATION 14.4 | 35.1 years STANDARD_DEVIATION 11.88 | 36.15 years STANDARD_DEVIATION 4.5 |
| Baseline food image ratings | 52.5 units on a scale STANDARD_DEVIATION 14.3 | 54.8 units on a scale STANDARD_DEVIATION 13.1 | 62.2 units on a scale STANDARD_DEVIATION 16 | 50.2 units on a scale STANDARD_DEVIATION 22.5 | 55.1 units on a scale STANDARD_DEVIATION 14.7 |
| BMI | 28.8 kg/m2 STANDARD_DEVIATION 3 | 22.5 kg/m2 STANDARD_DEVIATION 3 | 30.8 kg/m2 STANDARD_DEVIATION 5.5 | 24.2 kg/m2 STANDARD_DEVIATION 4.4 | 29.8 kg/m2 STANDARD_DEVIATION 4.6 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 1 Participants | 3 Participants | 5 Participants | 4 Participants | 13 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 8 Participants | 19 Participants | 9 Participants | 16 Participants | 52 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 10 Participants | 0 Participants | 8 Participants | 0 Participants | 18 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 3 Participants | 2 Participants | 0 Participants | 1 Participants | 6 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants | 0 Participants | 2 Participants | 1 Participants | 3 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 3 Participants | 3 Participants | 4 Participants | 4 Participants | 14 Participants |
| Race (NIH/OMB) White | 13 Participants | 17 Participants | 16 Participants | 14 Participants | 60 Participants |
| Region of Enrollment United States | 19 participants | 22 participants | 22 participants | 20 participants | 41 participants |
| Sex: Female, Male Female | 10 Participants | 14 Participants | 18 Participants | 12 Participants | 54 Participants |
| Sex: Female, Male Male | 9 Participants | 8 Participants | 4 Participants | 8 Participants | 29 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk |
|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 22 | 0 / 19 | 0 / 22 | 0 / 20 |
| other Total, other adverse events | 0 / 22 | 0 / 19 | 0 / 22 | 0 / 20 |
| serious Total, serious adverse events | 0 / 22 | 0 / 19 | 0 / 22 | 0 / 20 |
Outcome results
Primary
Change in Food Image Ratings
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.
Time frame: Baseline to within 10 minutes post-intervention
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Active Implicit Priming (MRI Sample) | Change in Food Image Ratings | -5.1 Score change from baseline | Standard Error 2.5 |
| Control Implicit Priming (MRI Sample) | Change in Food Image Ratings | -.3 Score change from baseline | Standard Error 2.2 |
| Active Implicit Priming (Behavioral-only Sample) | Change in Food Image Ratings | -6.8 Score change from baseline | Standard Error 1.3 |
| Control Implicit Priming (Behavioral-only Sample) | Change in Food Image Ratings | -2.7 Score change from baseline | Standard Error 1.4 |
p-value: 0.038ANOVA
p-value: 0.036ANOVA
Primary
Neuronal Response to Food Cues
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.
Time frame: Baseline to post-intervention
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Active Implicit Priming (MRI Sample) | Neuronal Response to Food Cues | 0.21 % BOLD signal change from baseline | Standard Deviation 0.45 |
| Control Implicit Priming (MRI Sample) | Neuronal Response to Food Cues | -0.07 % BOLD signal change from baseline | Standard Deviation 0.34 |
p-value: 0.01t-test, 2 sided
Secondary
Food Intake
Food intake during ad-lib lunch (kcals)
Time frame: 1 hour post-intervention
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Active Implicit Priming (MRI Sample) | Food Intake | 959.03 kcals | Standard Deviation 343.53 |
| Control Implicit Priming (MRI Sample) | Food Intake | 860.38 kcals | Standard Deviation 361.99 |
Comparison: Relationship between change in high-calorie food ratings and subsequent food intake (kcals).p-value: 0.04Pearson's correlation
Comparison: Relationship between change in high-calorie food ratings and subsequent food intake (kcals).p-value: 0.92Pearson's correlation