PET-study on the Role of the Reward System in Weight Loss After Bariatric Surgery

Study Overview
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Brief Summary
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Bariatric surgery (BS) is currently the most effective treatment in severe obesity. However, a considerable percentage of patients undergoing BS fail to lose sufficient weight or regain weight after initial weight loss during long-term follow-up, which may be attributed to personality traits and pathological eating behaviour. Previous positron emission tomography (PET) studies have shown reduced dopamine D2 receptor availability in obese patients and upregulation of this availability following successful BS in the brain's reward system. Dopamine D2 receptor availability in patients with unsuccessful BS has not been investigated to date.

Official Title
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PET-study on the Role of the Reward System in Weight Loss After Bariatric Surgery

Conditions
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Obesity

Intervention / Treatment
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* Other: standardized liquid mixed meal Nutridrink®


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Bariatric surgery 24-36 months prior to the study Adult (over 18y old) Mentally capable to understand the consequences of the procedure and make his or her own choice without coercion Able to undergo PET and MRI, according to the investigator's assessment Native speaking Able to participate in follow-up Written informed consent Exclusion Criteria: Presence of a DSM-IV axis 1 disorder The use of drugs that bind to dopamine D2/3 receptors, including various classes of antipsychotics and antidepressants History of stroke, brain tumor, Parkinson's Disease or dementia History of head trauma with loss of consciousness Alcohol or substance abuse in the last 6 months Alcohol consumption 24h prior to PET scanning Smoking or other forms of nicotine intake 12 hours prior to PET scanning Use of anorectic drugs in the last 6 months Current pregnancy Medication for Diabetes Mellitus Claustrophobia The presence of implanted metal objects of the type which may concentrate radiofrequency fields or cause tissue damage from twisting in a magnetic field (such as certain implanted devices, shrapnel, ocular metal shavings) Patients with a bodyweight > 200kg will be excluded to ensure the maximum load of the camera bed of the PET-scanner (227 kg) is not exceeded.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Unsuccessful BS (Total Weight Loss (TWL) < 20%)<br>Fifteen who had unsuccessful BS (Total Weight Loss (TWL) < 20%) | Other: standardized liquid mixed meal Nutridrink®<br>* Administration of food in controlled situation<br>|
| Experimental: Successful BS (TWL > 25%).<br>Fifteen who had successful BS (TWL > 25%). | Other: standardized liquid mixed meal Nutridrink®<br>* Administration of food in controlled situation<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in [11C]-raclopride binding potential in the brain's reward system between study groups before and after a food challenge. | Pre- and post-eating changes in dopamine D2 receptor availability as indexed by the [11C]-raclopride binding potential in the brain's reward system between subjects who underwent successful vs unsuccessful bariatric surgery | -50 minutes (before start of PET scanning), 0 minutes (during PET break, before mixed meal), 30 minutes (after second phase of PET-scanning) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The correlation between [11C]-raclopride binding potential in the brain's reward system and of questionnaires and diaries | The correlation between questionnaires on eating habits (EDE-Q, REO, YFAS) and quality of life (OBESI-Q) in patients who had successful vs unsuccessful BS and [11C]-raclopride binding potential. | Pre-intervention | 
| The correlation between [11C]-raclopride binding potential in the brain's reward system and of gut hormones. | The relation between fasting or fed (gut) hormone concentrations and dopamine D2 receptor availability in the reward system. | -50 minutes (before start of PET scanning), 0 minutes (during PET break, before mixed meal), 30 minutes (after second phase of PET-scanning), 60 - 90 - 120 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Obesity, Reward system, PET-scan, [11C]-Raclopride