A Phase 1 interventional study of Milkshake and NeuroEXPLORER in Obesity, sponsored by Yale University. Not yet recruiting at 1 site in United States. Open to participants aged 50 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by Yale University · Phase 1, Interventional, and Basic science
This study measures the brain's dopamine response to milkshake consumption in people with a healthy weight and people with obesity and examines whether this response differs between the two groups. Dopamine release will be measured using ultra-high-resolution positron emission tomography (PET) imaging with the NeuroEXPLORER scanner. The study will also examine how the dopamine response relates to hormonal responses measured at the same time and to participants' food intake behavior.
This study aims to address three key questions: (1) whether the two phases of dopamine release in the striatum, a brain region involved in reward and motivation, during and after milkshake consumption differ between people with a healthy weight and people with obesity, and between men and women; (2) how metabolic and hormonal responses relate to dopamine release; and (3) whether dopamine-related networks outside the striatum differ between weight groups and predict eating behavior. These findings may improve our understanding of overeating and obesity and help inform the development of treatments that target the brain's dopamine system.
Each participant will complete four visits:
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's planned enrollment of 100 is above the median of 67 across 9,006 interventional studies indexed under Obesity.
Browse Obesity studies →Yale University is the lead sponsor of 1,770 studies on the registry; 294 are open to participants now.
Of its 221 completed or terminated interventional studies of FDA-regulated products, 129 (58%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Four visits per participant: screening, PET practice session, MRI+behavioral assessment, milkshake+PET scan.
Other: Milkshake · Device: NeuroEXPLORER · Drug: [11C]raclopride
Four visits per participant: screening, PET practice session, MRI+behavioral assessment, milkshake+PET scan.
Other: Milkshake · Device: NeuroEXPLORER · Drug: [11C]raclopride
Strawberry, banana, chocolate, or vanilla flavored, delivered through a gustometer during the practice session and PET scan.
A next-generation ultra-high-performance dedicated human brain PET scanner.
Also known as: Ultra high resolution PET scan
Carbon-11 radiolabeled PET ligand with high affinity and selectivity for postsynaptic dopamine receptors; one of the standard radiotracers for measuring dopamine release in humans.
Also known as: injection
Dopamine (DA) release
Orosensory and post-ingestive DA release in the ventral and dorsal striatum during and after milkshake consumption
Time frame: Visit 4, approximately week 4. Baseline D2/3R binding potential will be assessed at T=30'. PET time-activity curves are then measured continuously for 60 minutes from milkshake onset.
Time to onset of DA peaks
Time to onset of orosensory and post-ingestive DA peaks in the ventral and dorsal striatum
Time frame: Visit 4, approximately week 4. PET time-activity curves are measured continuously for 60 minutes from milkshake onset (30-90 minutes after initiation of radiotracer administration).
Duration of DA peaks
Duration of orosensory and post-ingestive DA peaks in the ventral and dorsal striatum
Time frame: Visit 4, approximately week 4.PET time-activity curves are measured continuously for 60 minutes from milkshake onset (30-90 minutes after initiation of radiotracer administration).
Time to onset of DA peaks between men and women
Time to onset of orosensory and post-ingestive DA peaks in the ventral and dorsal striatum
Time frame: Visit 4, approximately week 4. PET time-activity curves are measured continuously for 60 minutes from milkshake onset (30-90 minutes after initiation of radiotracer administration).
Duration of DA peaks between men and women
Duration of orosensory and post-ingestive DA peaks in the ventral and dorsal striatum
Time frame: Visit 4, approximately week 4. PET time-activity curves are measured continuously for 60 minutes from milkshake onset (30-90 minutes after initiation of radiotracer administration).
Magnitude of DA release between men and women
Magnitude of orosensory and post-ingestive DA peaks in the ventral and dorsal striatum
Time frame: Visit 4, approximately week 4. PET time-activity curves are measured continuously for 60 minutes from milkshake onset (30-90 minutes after initiation of radiotracer administration).
Glucose
To assess the relationship between the metabolic response to the milkshake and striatal dopamine release, we will use a machine learning approach including network analysis.
Time frame: Glucose will be collected after an overnight fast on the morning of the PET scan and at 7.5, 15, 30, and 45 minutes after milkshake onset at Visit 4, approximately week 4.
Insulin
To assess the relationship between the metabolic response to the milkshake and striatal dopamine release, we will use a machine learning approach including network analysis.
Time frame: Insulin will be collected after an overnight fast on the morning of the PET scan and at 7.5, 15, 30, and 45 minutes after milkshake onset at Visit 4, approximately week 4.
FFA
To assess the relationship between the metabolic response to the milkshake and striatal dopamine release, we will use a machine learning approach including network analysis.
Time frame: FFA will be collected after an overnight fast on the morning of the PET scan and at 7.5, 15, 30, and 45 minutes after milkshake onset at Visit 4, approximately week 4.
Gut peptides (tbd)
To assess the relationship between the metabolic response to the milkshake and striatal dopamine release, we will use a machine learning approach including network analysis.
Time frame: Gut peptides will be collected after an overnight fast on the morning of the PET scan and at 7.5, 15, 30, and 45 minutes after milkshake onset.
Yale Food Addiction Scale 2.0 score
Total score ranges from 0 to 11. Higher symptom counts indicate more symptoms of addictive-like eating.
Time frame: After screening (visit 1), the PET test session (visit 2), the questionnaire will be administered during visit 3 (duration 10 minutes); after completion of the MRI
Barratt Impulsiveness Scale (BIS-11) score
A 30-item self-report questionnaire designed to measure human impulsiveness as a multidimensional personality and behavioral trait. Total score range 30 to 120, with higher scores reflecting greater impulsiveness.
Time frame: After screening (visit 1), the PET test session (visit 2), the questionnaire will be administered during visit 3 (duration 10 minutes); after completion of the MRI
Dietary Fat and Free Sugar - Short Questionnaire (DFS)
A 26-item self-report tool to measure how often a person eats foods high in saturated fat and free sugar over the past 12 months. Total score range 26 to 130, with higher scores reflecting more frequent consumption of foods high in saturated fat and/or free sugars.
Time frame: After screening (visit 1), the PET test session (visit 2), the questionnaire will be administered during visit 3 (duration 10 minutes); after completion of the MRI
Change in Delay Discounting Task
A behavioral assessment (computer task) to determine reward sensitivity (how much a person devalues a reward as the wait time for it increases). Calculated as Discount rate (k). Higher k indicates greater preference for immediate rewards.
Time frame: The task will be administered at the PET Center after an overnight fast at baseline (before radio tracer administration) and after the PET scan at T=105' (duration of the task is 10 minutes)
Change in Iowa Gambling Task score
The Iowa Gambling Task is a behavioral task that assesses decision-making under uncertainty by asking participants to select cards from four decks with different rewards and losses. The net score is calculated by subtracting the number of selections from disadvantageous decks from the number of selections from advantageous decks.
Time frame: The task will be administered at the PET Center after an overnight fast at baseline (before radio tracer administration) and after the PET scan at T=115' (duration of the task is 15 minutes)
Behavioral Inhibition System/Behavioral Activation System Scale score
The Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) Scales assess sensitivity to punishment and reward. The questionnaire contains 24 items, including 20 scored items and 4 filler items. It yields four subscale scores: Behavioral Inhibition (7-28), BAS Drive (4-16), BAS Fun Seeking (4-16), and BAS Reward Responsiveness (5-20). Higher scores indicate greater sensitivity to punishment, stronger pursuit of goals, greater fun seeking, and greater responsiveness to reward, respectively.
Time frame: After screening (visit 1), the PET test session (visit 2), the questionnaire will be administered during visit 3 (duration 10 minutes); after completion of the MRI
Change in Visual Analogue Scale (VAS) score
VAS to assess hunger and satiety on a scale of 0-100. Higher hunger scores indicate greater hunger, while higher satiety/fullness scores indicate greater satiety/fullness
Time frame: The task will be administered at the PET Center after an overnight fast at baseline (before radio tracer administration) and after the PET scan at T=100' (duration of the task is 2 minutes)
Plan to share: Yes — Computer codes developed for MRI and PET analysis will be shared on the open-access GitHub platform to support reproducibility. The study protocol and clinical data generated from this study will be uploaded to ClinicalTrials.gov. De-identified neuroimaging and research data will be submitted to appropriate NIH data repositories in compliance with NIH data sharing requirements.
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drug tested here: Raclopride c-11