1. STARTING HYPOTHESES AND GENERAL OBJECTIVE HYPOTHESIS: The treatment of excess weight with a comprehensive program based on experimental knowledge about the functioning and modification of the impulsive and executive systems will be effective for the treatment of overweight and obesity. Thus, the neurocognitive training will reduce body mass index (BMI) in people with overweight and obesity, compared to a sham treatment and to only usual treatment. In addition, the neurocognitive program will improve other anthropometric measures (waist circumference, waist-to-hip and waist-to-height ratios), lifestyle behaviors (eating behavior and physical activity), as well as cognitive processes (approach-avoidance bias, food inhibition, food liking and delay of gratification). Finally, the program will show its efficiency in the economic balance of cost-effectiveness and cost-utility.
GENERAL OBJECTIVE: To determine the effectiveness of a comprehensive neurocognitive program for the treatment of excess weight.
1.1. Specific Aims: Objective 1: To examine the effectiveness of a comprehensive neurocognitive training to reduce BMI in the short, medium and long term (post-treatment, 3-month follow-up and 6-month follow-up).
Objective 2: To study the effectiveness of the comprehensive neurocognitive program to change food behaviors, physical activity and body measures.
Objective 3: To investigate which active ingredients have an impact on the results of the program as outlined below:
3.1. To study the effectiveness of the impulsive training (approach-avoidance bias modification and improvement of inhibitory control) to reduce the approach bias to appetitive foods, increase the inhibitory control, improve the food decision making and modify the valuation of healthy and unhealthy foods.
3.2. To study the effectiveness of reflexive training (implementation of intentions and episodic future thinking) to improve behaviors related to implementation of intentions in healthy eating and physical activity, and to increase delay of gratification.
3.3. To compare the effectiveness of the neurocognitive training (impulsive and reflexive) to reduce BMI and body measures, and to improve food behaviors and physical activity.
3.4. To study the variables related to cognition, affect, stress and non-homeostatic food intake, motivation and personality to predict or mediate the intervention results.
Objective 4: To conduct an economic evaluation analysis of cost-effectiveness and cost-utility of the neurocognitive training in people with overweight and obesity, and analyze what budgetary impact would imply for the Spanish National Health System.
2. METHODOLOGY
2.1. Design: Randomized controlled trial of parallel groups.
2.2. Participants: The participants (N=150) will be randomly allocated to three groups: experimental group (neurocognitive intervention; n=50), active control group (sham intervention; n=50), and control group (treatment as usual; n=50).
A randomization (minimization) through the software Minimizer® will be performed to avoid imbalances between the groups in age, sex, and BMI.
2.3. Interventions: Pre-treatment interventions (all groups): Participants will participate in a group Motivational Interviewing session, and will receive an individualized diet and a physical exercise planning for 6 weeks. Also, informative videos and brochures will be provided. Further, participants will participate in two group informative sessions (one with a nutritionist and another with a physical exercise instructor). These two meetings will be recorded and made available for all participants.
Whatsapp groups will be created to promote participants' social interactions.
Neurocognitive program (experimental and active control groups). Duration: 4 weekly sessions of about 60-90 minutes.
Phase 1. Impulsive training will include: (i) Approach-avoidance bias modification with the Tilt Task app; (ii) Inhibition training with the Food Trainer task app.
Phase 2. Reflexive training will include: (iii) Implementation of Intentions; (iv) Episodic Future Thinking.
The order of phases 1 \& 2 will be counterbalanced. One task will be trained in each session, and participants will practice that task daily at home for one week (until the next session). They will receive daily reminders on their mobile phones. A weekly pre-post assessment will be conducted for each trained task.
Post-treatment interventions (all groups): Participants will have the opportunity to attend a second group meeting with the nutritionist and another with the physical activity professional to receive information and ask questions about how to maintain long-term healthy habits on diet and physical exercise. These meetings will be recorded and made available for all participants. They will also be provided with new videos with guidelines about how to maintain a healthy long-lasting eating and exercise. The aim is that participants be autonomous and can develop their own diet and exercise planning.
2.4. Outcome measures: Body Mass Index will be the main outcome measure. Secondary outcomes will measure changes in cognitive, lifestyle behaviors and body measures. Mediating and moderating variables will include affect, stress and nonhomeostatic eating, executive functions, motivation, personality, adherence to diet and physical exercise, and clinical variables. Further, assessment will include screening and descriptive variables, and measures to calculate cost-effectiveness, cost-utility and budget impact of the intervention program.
3. PROCEDURE All assessments and intervention sessions will be delivered online. Inclusion and exclusion criteria will be checked through the data collected in a questionnaire of sociodemographic and clinical variables. Further, psychopathology exclusion criteria will be tested with two questionnaires to measure depression, anxiety, and stress symptoms as well as binge eating and bulimia (DASS-21 and QEWP-5), and a short clinical interview by phone and/or information requested by email in those cases where there are doubts about any of the aspects collected through the online instruments.
All candidates who meet the criteria will attend an information meeting about the project in which they will receive written and oral information, and will be asked for their informed consent. Then, participants will be randomly assigned to groups before the pre-treatment assessment sessions. The three groups of the study (intervention, active control and control) will complete all of the evaluations, as well as the follow-ups (see below). Further, all groups will received the pre-treatment interventions (Motivational Interviewing, nutrition and physical activity sessions). What will differentiate the groups will be, therefore, the treatment: neurocognitive intervention vs. sham vs. usual treatment. The control groups will be offered the treatment sessions (without the assessment components) after the end of the 6-month follow-up.
Sessions will be developed in groups of 5-6 persons. If a participant misses a session he/she can attend another one within 3-4 days. There will be 10 experimental groups of active training = 50 participants; 10 active control groups of sham training = 50 participants; and 10 control groups = 50 participants. The program will comprise 8 weeks including three assessments (pre, intermedium and post-treatment), four intervention sessions, as well as pre-treatment and post-treatment intervention sessions. Also, two follow-up sessions at 3 and 6 months after treatment (see below). Sessions will last about 1 hour and a half.
Sessions will consist of the following:
1. Informative session (session 1; week 0): All participants will be informed about the aims and the procedure of the research, and they will provide written informed consent.
2. Pre-treatment assessment (session 2, week 1): All participants will complete the instruments to obtain the main and secondary outcomes, the potential mediators/moderators, and economic measures.
3. Pre-treatment interventions (sessions 3, 4 and 5, week 2):
3.1. Motivational interviewing session: This 90-minute session will be developed in a group format of 5-6 participants.
3.2. Nutrition session: Participants will receive an individualized diet for the following 6 weeks. Videos and brochures about nutrition will be provided, and participants will assist a 60-minute group session with the nutritionist to match and complete relevant information on nutrition and excess weight.
3.3. Physical activity session: Participants will receive physical activity recommendations for the following 6 weeks. Videos and brochures about physical exercise will be provided, and participants will assist a 60-minute group session with the physical exercise instructor to match and complete relevant information on exercise and excess weight.
4. Intervention sessions (sessions 6, 7, 9 and 10; weeks 3, 4, 6 and 7): All sessions will start with Visual Analogue Scales to evaluate hunger, nutrition and physical activity. Each intervention session will be preceded by its pre-treatment evaluation, and followed by its post-treatment evaluation after a week of daily training. The pre and post-treatment evaluation of the impulsive training will be measured by the approach-avoidance bias (with the Tilt-Task app), food choice, the inhibitory control (with the Food Trainer app) and food liking. The pre and post-treatment evaluation of the reflexive training will be measured by the Now or Later questionnaire for the episodic future thinking training, and the self-registration of nutrition and physical exercise for the implementation of intentions.
5. Intermediate assessment (session 8; week 5): This assessment will allow the comparison between the interventions for the impulsive and reflexive trainings.
6. Post-treatment assessment (session 11, week 8): To evaluate the effectiveness of the whole intervention program, the measures of the pre-treatment assessment will be repeated.
7. Post-treatment interventions (session 12, week 8): After the post-treatment assessment, participants will have the opportunity to have a second 60-minute group meeting with the nutritionist and another with the physical activity professional, and they will be provided with new 20-minute videos about how to maintain a healthy long-lasting eating and exercise.
After all interventions, participants will be asked to complete a debriefing to register their thoughts and subjective experience about the program.
8. Follow-up (sessions 13 and 14, week 20 and week 32): Follow-ups at 3 and 6 months after the intervention will include the instruments to obtain the main and secondary outcome measures. Besides, every month after the end of the treatment, participants will be contacted by email and mobile message to maintain adherence.
Participants will be instructed to eat two hours before all evaluation (pre, intermediate and post-treatment, and the two follow-ups) and neurocognitive sessions. Pre, intermediate and post-treatment assessments will be carried out at the same hour.
