Healthy VolunteersNCT07920952
Effects of Ad Libitum Ultra-Processed Diet on Brain Dopamine in Humans
A study testing [11C] raclopride, liquid nutritive stimulus and Tasteless Oral Stimulus Solution in people with Healthy Volunteers, run by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at 1 site in United States.
Trial summary
Background: Dopamine is a chemical that the brain makes when a person expects a reward. Researchers want to learn more about how eating different types of food affects dopamine levels in the brain. Objective: To test how eating different foods affects dopamine levels in the brains of healthy people. Read more about this study
- Who is it for?
- Ages 18 to 45 years
- Conditions the study is for
- Healthy Volunteers
- What is being tested?
- [11C] raclopride, liquid nutritive stimulus and Tasteless Oral Stimulus Solution
- Type of treatment
- Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 140 participants
- Where
- 1 siteUnited States
- Study dates
- 11 Nov 2026to 10 Nov 2030
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 45 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- In order to be eligible to participate in this study, an individual must meet all of the following criteria:
- Aged 18 to 45 years old
- In good general health as evidenced by medical history
- Weight stable (< +/- 5% change in last 6 months), based on self-report
- BMI
- Cohort 1: 18.5 - 24.9 kg/m^2
- Cohort 2: >= 18.5 kg/m^2
Who cannot join
- An individual who meets any of the following criteria will be excluded from participation in this study:
- Body weight > 400 lbs. (weight limit of PET scanner)
- History or current self-report of conditions that may influence appetite, in the opinion of the study investigators, including but not limited to cancer, diabetes mellitus, evidence of metabolic dysfunction, changes in senses of smell or taste (e.g., covid-related), or metabolic/bariatric surgery
- History or current neurological, mood, eating, or substance use disorders by self-report, history/physical, Eating Disorder Examination Questionnaire, and/or DSM-5 Cross-cutting symptom measure.
- Measured resting energy expenditure +/- 30% of that predicted by Mifflin St-Jeor equation.
- Uncontrolled hypertension, with blood pressure >140/90 mm Hg
Show all 19Show fewer
- Pregnancy or lactation
- Known allergic reactions to components of the PET agent, [C-11] raclopride.
- Having had previous radiation exposure within the last year for either medical or research purposes (e.g. X-rays, PET scans, etc.) that would exceed research limits. Excessive radiation exposure will be determined at the discretion of the PI and/or study team
- Inability or unwillingness (e.g. due to claustrophobia) to tolerate lying flat on their back for extended periods of time in PET/MR or MRI scanner or (Cohort 1 only) inability to tolerate swallowing drops of liquid delivered onto tongue while lying down on bed.
- Having metal implants incompatible with MRI (for example, pacemakers, metallic prostheses such as cochlear implants or heart valves, shrapnel fragments, etc.).
- Left-handedness, by self-report and confirmation via Edinburgh Handedness Survey
- Self-report of daily alcohol intake > 3 drinks (males) or > 2 drinks (females)
- Current nicotine use (e.g. cigarette, vaping) determined by participant report or nicotine dependence confirmed by Fagerstrom Nicotine Dependence (score >= 4)
- Current use of medications or drugs of abuse which may influence appetite or have central effects, in the opinion of study investigators
- Caffeine consumption > 300 mg/day (roughly >=3 cups coffee or 2-3 energy drinks)
- Significant dietary restrictions, based on evaluation by nutrition staff and results of nutrition screener (rating fewer than 75% of foods listed as a 4 or higher score on The Food Enjoyment Questionnaire)
- Unable or unwilling to provide informed consent
- Unable or unwilling to adhere to study diet, procedures, schedule, and lifestyle considerations
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
National Institutes of Health Clinical Center
Bethesda, Maryland, 20892
Valerie Darcey, 301-402-9689, valerie.darcey@nih.gov
About this study
Background:
Dopamine is a chemical that the brain makes when a person expects a reward. Researchers want to learn more about how eating different types of food affects dopamine levels in the brain.
Read more
Objective:
To test how eating different foods affects dopamine levels in the brains of healthy people.
Eligibility:
Healthy people aged 18 to 45 years old.
Design:
Participants will be divided into 2 groups (cohorts). Both will have overnight stays in the clinic.
All participants will be screened. They will talk to a dietitian about their eating habits. They will have a test of how much energy their body uses: They will lie on a table with a clear hood over their heads to measure the gases as they breathe.
During the 3 weeks before participants stay at the clinic, a dietitian will call at 3 random times to ask what they ate the day before. They will complete questionnaires. Cohort 1 will wear a device to track their step count for at least 7 days; these participants will be given food to eat for 2 days before they stay in the clinic.
Cohort 1 will stay in the clinic for 14 days. They will eat as much or as little as they would like on 2 different diets for 5 days each and a normal diet on the other days. They will have blood collected multiple times. They will have 2 d ifferent types of imaging scans. For 1 type, they will receive a drug through a vein to show how much dopamine is in their brains.
Cohort 2 will stay in the clinic for 2 days. They will eat only the foods provided. They will have imaging scans before and after drinking a milkshake. For both scans, they will receive a drug through a vein to show how much dopamine is in their brains. They will have blood collected multiple times.
Read the detailed description
Study Description:
In this single-site study, we will recruit a cohort of 32 adult volunteers to a randomized crossover diet study to investigate change in dopamine D2 receptor availability (via [11C]raclopride binding potential). During their participation, after a 2-day outpatient stabilization diet, participants will be admitted for a 14-day, 13-night inpatient stay at the NIH Clinical Center. Following 2 days of inpatient stabilization diet, participants will consume two ad libitum test diets with distinct proportions of ultra-processed food for 5 days each in random order separated by 1 day of stabilization diet. We will collect information via Positron Emission Tomography (PET) about dopamine D2 receptor availability under fasting conditions and dopamine response to an oral stimulus solution. Additionally, magnetic resonance spectroscopy and imaging (MRS, MRI) will be used to collect information on changes in brain GABA tone, white matter hyperintensities, brain iron content, and brain activity in response to the two test diets. Further, we will additionally recruit a cohort of 36 adult volunteers for a 2 day/1night stay at the Clinical Center to measure dopamine D2 receptor availability in the extended post ingestive state to determine whether dopamine release may be quantified in this period of the postprandial state.
Objectives:
- Primary Objective: To determine the impact of two 5-day ad libitum test diets differing in proportion of ultra-processed, energy-dense, hyper-palatable foods on fasting striatal [11C]raclopride dopamine D2 receptor binding potential (D2BP) as well as the magnitude of any change from baseline.
- Secondary Objective: To determine differences in spatiotemporal components of striatal dopamine response (rDA) to a milkshake after two 5-day ad libitum test diets matched for presented nutrients but different in proportion of ultra-processed, energy-dense, hyperpalatable foods.
- Secondary Objective: To determine change in whole striatal dopamine D2BP in the extended post-ingestive period, beginning 1.5 - 3 hours following consumption of a UPF milkshake, as measured by [11C]raclopride
Endpoints:
- Primary Endpoint: Dopamine D2 receptor binding potential (D2BP) in the striatum after two test diets will be quantified during steady state portion of 20mCi [11C]raclopride infusion PET neuroimaging.
- Secondary Endpoint: Regionally and temporally specific dopamine response to in-scanner milkshake consumption and digestion after 5 days of each test diet will be determined voxelwise (spatial) over a duration of [11C]raclopride infusion (temporal), compared to equivalent endpoints for "tasteless" oral stimulus.
- Secondary Endpoint: D2BP in the striatum will be quantified using a bolus of 20mCi [11C]raclopride in both the overnight fasted state and delayed post-ingestive state for each participant.
- Conditions
- Healthy Volunteers
- Being tested
- [11C] raclopride, liquid nutritive stimulus, Tasteless Oral Stimulus Solution, Minimally Processed Diet, Ultra Processed Diet
- Keywords
- Raclopride, Ultra-Processed Foods, Neuroimaging, Dopamine Response
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
[11C] racloprideDrug
The drug is intended for use as a radiopharmaceutical for positron emission tomography (PET) administered at a maximum prescribed dose of 20mCi and will be administered intravenously via indwelling catheter
liquid nutritive stimulusOther
The ~8 oz liquid meal will be high in both dietary fat and sugar and ultra-processed designation based on ingredients and will be prepared by the NIH Clinical Center Metabolic Kitchen for participant consumption during the PET scans at the end of both test dietary intervention periods (Cohort 1) or for consumption between the PET scans (Cohort 2).
Tasteless Oral Stimulus SolutionOther
The control stimulus is a non-rewarding tasteless solution with viscosity distinct from pure water (i.e., artificial saliva). Four dilutions of 25mM potassium chloride + 2.5mM sodium bicarbonate will be prepared by NIH Clinical Center Pharmacy for participant oral stimulus taste test
Minimally Processed DietOther
The minimally processed diet will derive ~80% of calories from minimally processed foods and will contain no ultra-processed foods, (NOVA 1-3), as defined by the degree, extent, and purpose of processing according to the NOVA classification system. The minimally processed diet will be matched to the ultra-processed diet for presented macronutrients, sugar, sodium, and fiber. This diet will be low in both non-beverage energy density and hyper-palatable foods
Ultra Processed DietOther
The ultra-processed diet will derive ~80% of energy from ultra-processed foods (NOVA 4), as defined by the degree, extent, and purpose of processing according to the NOVA classification system. The ultra processed diet will be matched to the minimally processed diet for presented macronutrients, sugar, sodium, and fiber. This diet will be high in both non-beverage energy density and hyper-palatable foods.
Baseline DietOther
The baseline (control) diet will be composed of 50% of energy from ultra-processed foods while matching distribution of macronutrients presented in test diets and total sugar, sodium, and fiber). Energy needs will be estimated using resting energy expenditure multiplied by an appropriate activity factor collected at screening visit to facilitate production by the NIH Metabolic Kitchen.
| Study group | Role | What they receive |
|---|---|---|
| MPF-UPF | Experimental | Participants will be randomized to the one of two diet sequences (study arms: UPF-MPF vs MPF-UPF) by NIH dietitians after enrollment, in advance of admission. A total of n=32 participants will be evenly grouped into 16 batches according to date of inpatient admission. Within each batch of 2 participants, participants will be randomly assigned to one of the two diet sequences, ensuring any order effects will be counterbalanced and maintaining balance across diet sequence assignments. Receives: Drug: [11C] raclopride; Other: liquid nutritive stimulus; Other: Tasteless Oral Stimulus Solution; Other: Minimally Processed Diet; Other: Baseline Diet |
| UPF-MPF | Experimental | Participants will be randomized to the one of two diet sequences (study arms: UPF-MPF vs MPF-UPF) by NIH dietitians after enrollment, in advance of admission. A total of n=32 participants will be evenly grouped into 16 batches according to date of inpatient admission. Within each batch of 2 participants, participants will be randomly assigned to one of the two diet sequences, ensuring any order effects will be counterbalanced and maintaining balance across diet sequence assignments. Receives: Drug: [11C] raclopride; Other: liquid nutritive stimulus; Other: Tasteless Oral Stimulus Solution; Other: Ultra Processed Diet; Other: Baseline Diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Dopamine D2 receptor binding potential (D2BP) during steady portion of [11C]raclopride infusion PET neuroimaging
Fasting (steady state) whole striatal dopamine D2 receptor binding at the conclusion of three diet periods (on 4th day of control diet, after 5 full days ad libitum UPF, and after 5 full days ad libitum MPF)
Measured: 5 days
Secondary outcomes (2)
The magnitude of striatal dopamine responses to orosensory and post-ingestive milkshake exposure
Measured at the conclusion of three diet periods (on 4th day of control diet, after 5 full days ad libitum UPF, and after 5 full days ad libitum MPF).
Measured: 5 days
The difference between striatal dopamine D2 receptor binding potential
Measured while fasting and 1.3 -3 hours after a palatable liquid meal (Cohort 2).
Measured: 90-180 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Nov 2026
- Study start11 Nov 2026 (estimated)
- Primary completion10 Nov 2030 (estimated)
- Study completion10 Nov 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy VolunteersStudies of the same condition, open and under way.
- More trials run by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)The sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 140 participants (estimated)
Sponsor and investigators
- Sponsor type
- US National Institutes of Health
- Responsible party
- Sponsor
- Investigators
- Valerie L Darcey, Principal investigator, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07920952
- Sponsor's protocol ID
- 10002388
- Other IDs
- 002388-DK
- Status last verified
- 27 Oct 2026
- First submitted
- 5 Nov 2026
- Last updated
- 6 Nov 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Data published in Harvard Dataverse (https://dataverse.harvard.edu/) will be accessible to the research community for the long-term. Terms of access to data to require requestors to log in and provide information including their identity and intended use to initiate an access request to Dr. Darcey, the PI.
Study at a glance
From the registry record, last updated by the sponsor on 6 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Ad Libitum Ultra-Processed Diet on Brain Dopamine in Humans
- ClinicalTrials.gov ID
- NCT07920952
- Acronym / sponsor ID
- 10002388
- Conditions
- Healthy Volunteers
- Keywords
- Raclopride, Ultra-Processed Foods, Neuroimaging, Dopamine Response
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 140 participants (estimated)
- Lead sponsor
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)US National Institutes of Health
- Study start
- 11 Nov 2026 (estimated)
- Primary completion
- 10 Nov 2030 (estimated)
- Study completion
- 10 Nov 2030 (estimated)
- First posted
- 6 Nov 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Background:
Dopamine is a chemical that the brain makes when a person expects a reward. Researchers want to learn more about how eating different types of food affects dopamine levels in the brain.
Objective:
To test how eating different foods affects dopamine levels in the brains of healthy people.
Eligibility:
Healthy people aged 18 to 45 years old.
Design:
Participants will be divided into 2 groups (cohorts). Both will have overnight stays in the clinic.
All participants will be screened. They will talk to a dietitian about their eating habits. They will have a test of how much energy their body uses: They will lie on a table with a clear hood over their heads to measure the gases as they breathe.
During the 3 weeks before participants stay at the clinic, a dietitian will call at 3 random times to ask what they ate the day before. They will complete questionnaires. Cohort 1 will wear a device to track their step count for at least 7 days; these participants will be given food to eat for 2 days before they stay in the clinic.
Cohort 1 will stay in the clinic for 14 days. They will eat as much or as little as they would like on 2 different diets for 5 days each and a normal diet on the other days. They will have blood collected multiple times. They will have 2 d ifferent types of imaging scans. For 1 type, they will receive a drug through a vein to show how much dopamine is in their brains.
Cohort 2 will stay in the clinic for 2 days. They will eat only the foods provided. They will have imaging scans before and after drinking a milkshake. For both scans, they will receive a drug through a vein to show how much dopamine is in their brains. They will have blood collected multiple times.
Detailed description
Study Description:
In this single-site study, we will recruit a cohort of 32 adult volunteers to a randomized crossover diet study to investigate change in dopamine D2 receptor availability (via [11C]raclopride binding potential). During their participation, after a 2-day outpatient stabilization diet, participants will be admitted for a 14-day, 13-night inpatient stay at the NIH Clinical Center. Following 2 days of inpatient stabilization diet, participants will consume two ad libitum test diets with distinct proportions of ultra-processed food for 5 days each in random order separated by 1 day of stabilization diet. We will collect information via Positron Emission Tomography (PET) about dopamine D2 receptor availability under fasting conditions and dopamine response to an oral stimulus solution. Additionally, magnetic resonance spectroscopy and imaging (MRS, MRI) will be used to collect information on changes in brain GABA tone, white matter hyperintensities, brain iron content, and brain activity in response to the two test diets. Further, we will additionally recruit a cohort of 36 adult volunteers for a 2 day/1night stay at the Clinical Center to measure dopamine D2 receptor availability in the extended post ingestive state to determine whether dopamine release may be quantified in this period of the postprandial state.
Objectives:
- Primary Objective: To determine the impact of two 5-day ad libitum test diets differing in proportion of ultra-processed, energy-dense, hyper-palatable foods on fasting striatal [11C]raclopride dopamine D2 receptor binding potential (D2BP) as well as the magnitude of any change from baseline.
- Secondary Objective: To determine differences in spatiotemporal components of striatal dopamine response (rDA) to a milkshake after two 5-day ad libitum test diets matched for presented nutrients but different in proportion of ultra-processed, energy-dense, hyperpalatable foods.
- Secondary Objective: To determine change in whole striatal dopamine D2BP in the extended post-ingestive period, beginning 1.5 - 3 hours following consumption of a UPF milkshake, as measured by [11C]raclopride
Endpoints:
- Primary Endpoint: Dopamine D2 receptor binding potential (D2BP) in the striatum after two test diets will be quantified during steady state portion of 20mCi [11C]raclopride infusion PET neuroimaging.
- Secondary Endpoint: Regionally and temporally specific dopamine response to in-scanner milkshake consumption and digestion after 5 days of each test diet will be determined voxelwise (spatial) over a duration of [11C]raclopride infusion (temporal), compared to equivalent endpoints for "tasteless" oral stimulus.
- Secondary Endpoint: D2BP in the striatum will be quantified using a bolus of 20mCi [11C]raclopride in both the overnight fasted state and delayed post-ingestive state for each participant.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| MPF-UPF | Experimental | Drug: [11C] raclopride, Other: liquid nutritive stimulus, Other: Tasteless Oral Stimulus Solution, Other: Minimally Processed Diet, Other: Baseline DietParticipants will be randomized to the one of two diet sequences (study arms: UPF-MPF vs MPF-UPF) by NIH dietitians after enrollment, in advance of admission. A total of n=32 participants will be evenly grouped into 16 batches according to date of inpatient admission. Within each batch of 2 participants, participants will be randomly assigned to one of the two diet sequences, ensuring any order effects will be counterbalanced and maintaining balance across diet sequence assignments. |
| UPF-MPF | Experimental | Drug: [11C] raclopride, Other: liquid nutritive stimulus, Other: Tasteless Oral Stimulus Solution, Other: Ultra Processed Diet, Other: Baseline DietParticipants will be randomized to the one of two diet sequences (study arms: UPF-MPF vs MPF-UPF) by NIH dietitians after enrollment, in advance of admission. A total of n=32 participants will be evenly grouped into 16 batches according to date of inpatient admission. Within each batch of 2 participants, participants will be randomly assigned to one of the two diet sequences, ensuring any order effects will be counterbalanced and maintaining balance across diet sequence assignments. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- In order to be eligible to participate in this study, an individual must meet all of the following criteria:
- Aged 18 to 45 years old
- In good general health as evidenced by medical history
- Weight stable (< +/- 5% change in last 6 months), based on self-report
- BMI
Key exclusion criteria (19 listed)
- An individual who meets any of the following criteria will be excluded from participation in this study:
- Body weight > 400 lbs. (weight limit of PET scanner)
- History or current self-report of conditions that may influence appetite, in the opinion of the study investigators, including but not limited to cancer, diabetes mellitus, evidence of metabolic dysfunction, changes in senses of smell or taste (e.g., covid-related), or metabolic/bariatric surgery
- History or current neurological, mood, eating, or substance use disorders by self-report, history/physical, Eating Disorder Examination Questionnaire, and/or DSM-5 Cross-cutting symptom measure.
- Measured resting energy expenditure +/- 30% of that predicted by Mifflin St-Jeor equation.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| [11C] racloprideThe drug is intended for use as a radiopharmaceutical for positron emission tomography (PET) administered at a maximum prescribed dose of 20mCi and will be administered intravenously via indwelling catheter | Drug | MPF-UPF, UPF-MPF |
| liquid nutritive stimulusThe ~8 oz liquid meal will be high in both dietary fat and sugar and ultra-processed designation based on ingredients and will be prepared by the NIH Clinical Center Metabolic Kitchen for participant consumption during the PET scans at the end of both test dietary intervention periods (Cohort 1) or for consumption between the PET scans (Cohort 2). | Other | MPF-UPF, UPF-MPF |
| Tasteless Oral Stimulus SolutionThe control stimulus is a non-rewarding tasteless solution with viscosity distinct from pure water (i.e., artificial saliva). Four dilutions of 25mM potassium chloride + 2.5mM sodium bicarbonate will be prepared by NIH Clinical Center Pharmacy for participant oral stimulus taste test | Other | MPF-UPF, UPF-MPF |
| Minimally Processed DietThe minimally processed diet will derive ~80% of calories from minimally processed foods and will contain no ultra-processed foods, (NOVA 1-3), as defined by the degree, extent, and purpose of processing according to the NOVA classification system. The minimally processed diet will be matched to the ultra-processed diet for presented macronutrients, sugar, sodium, and fiber. This diet will be low in both non-beverage energy density and hyper-palatable foods | Other | MPF-UPF |
| Ultra Processed DietThe ultra-processed diet will derive ~80% of energy from ultra-processed foods (NOVA 4), as defined by the degree, extent, and purpose of processing according to the NOVA classification system. The ultra processed diet will be matched to the minimally processed diet for presented macronutrients, sugar, sodium, and fiber. This diet will be high in both non-beverage energy density and hyper-palatable foods. | Other | UPF-MPF |
| Baseline DietThe baseline (control) diet will be composed of 50% of energy from ultra-processed foods while matching distribution of macronutrients presented in test diets and total sugar, sodium, and fiber). Energy needs will be estimated using resting energy expenditure multiplied by an appropriate activity factor collected at screening visit to facilitate production by the NIH Metabolic Kitchen. | Other | MPF-UPF, UPF-MPF |
Primary outcome
Dopamine D2 receptor binding potential (D2BP) during steady portion of [11C]raclopride infusion PET neuroimaging
Time frame: 5 days
Fasting (steady state) whole striatal dopamine D2 receptor binding at the conclusion of three diet periods (on 4th day of control diet, after 5 full days ad libitum UPF, and after 5 full days ad libitum MPF)
2 secondary outcomes
The magnitude of striatal dopamine responses to orosensory and post-ingestive milkshake exposure
Time frame: 5 days
The difference between striatal dopamine D2 receptor binding potential
Time frame: 90-180 minutes
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Nov 2026.
- NIH Clinical Center Detailed Web PageLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. Data published in Harvard Dataverse (https://dataverse.harvard.edu/) will be accessible to the research community for the long-term. Terms of access to data to require requestors to log in and provide information including their identity and intended use to initiate an access request to Dr. Darcey, the PI.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Valerie L Darcey principal investigator
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing [11C] raclopride, liquid nutritive stimulus and Tasteless Oral Stimulus Solution in people with Healthy Volunteers, run by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 19 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 6 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Nan Zhai, C.R.N.P. ((301) 827-3324, nan.zhai@nih.gov), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Dopamine D2 receptor binding potential (D2BP) during steady portion of [11C]raclopride infusion PET neuroimaging (time frame: 5 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Nov 2026.