HealthyPhase 4Caffeine-RACNCT06763172
Effects of Caffeine on Reinforcement Learning in Healthy Adults Using PET/MRI
A Phase 4 study testing Caffeine (200 mg) in people with Healthy and Caffeine, run by Hsiao-Ying Wey at 1 site in United States.
Trial summary
This research study aims to determine whether and how caffeine intake affects learning process through reward feedback compared to placebo. The data acquired from this study would improve our understanding on the consequence and mechanism of caffeine intake in the aspect of learning process. Read more about this study
- Who is it for?
- Ages 18 to 45 yearsHealthy volunteers can take part
- What is being tested?
- Caffeine (200 mg)
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 12 participants
- Where
- 1 siteUnited States
- Study dates
- 17 May 2023to 31 Dec 2026
- Phase
- Phase 4
- 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
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age ≥ 18 and ≤ 45.
- Habitual caffeine intake ≥ 100 mg and ≤ 450 mg daily.
- Non-smokers.
- Clinically healthy.
- Have normal vision or corrected to normal vision.
Who cannot join
- Pregnant or lactating women.
- Women using hormonal contraceptives.
- BMI < 18.5 or > 29.9
- Sleep disturbance or extreme chronotype.
- Urine test positive on one of the following substances: benzoylecgonine, morphine, d-Methamphetamine, d-Amphetamine, Benzodiazepines, Secobarbital, Methadone, Buprenorphine Glucuronide, Nortriptyline, MDMA, Oxycodone, PCP, Propoxyphene, and Cannabis/THC
- Diagnosis of depression, anxiety, psychosis, or neurologic disorders in the last 5 years.
Show all 18Show fewer
- Heart or cardiovascular diseases.
- Diabetes or other metabolic diseases.
- Under chronic medications, for instance, painkiller and steroid.
- Allergy to lactose (main ingredient of blank control dose)
- Incapable to operate the tasks or comprehend the study information in English.
- General MRI and PET safety exclusion criteria for all subjects:
- Metallic foreign bodies such as cardiac pacemakers, perfusion pumps, aneurysm clips, metallic tattoos anywhere on the body, tattoos near the eye.
- Pre-existing medical conditions including a likelihood of developing seizures or claustrophobic reactions
- Inability to lie flat on scanner bed for about 90 min as assessed by physical examination and medical history (e.g. arthritis)
- Recent exposure to radiation (i.e., PET from other research studies) that, when combined with this study, would be above the allowable limits
- Pregnancy or breastfeeding: A negative serum or urine pregnancy test is required on the day of the PET procedure
- Body weight of > 300 lbs (weight limit of the MRI scanner table)
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, 1 recruiting
- Recruiting
Athinoula A. Martinos Center for Biomedical Imaging
Charlestown, Massachusetts, 02129
Hsiao-Ying Wey, PhD, 617-724-1384, hsiaoying.wey@mgh.harvard.edu
hsiaoying.wey@mgh.harvard.edu
About this study
Official title: Measure Striatal Adenosine-dopamine Receptors Interactions: from Molecule to Behaviors
This research study aims to determine whether and how caffeine intake affects learning process through reward feedback compared to placebo. The data acquired from this study would improve our understanding on the consequence and mechanism of caffeine intake in the aspect of learning process.
Participants will perform a reinforcement learning task (i.e. Probabilistic Selection Task) and a motor inhibition task (i.e. Go/NoGo task) in a brain scan. The scan will be done with the Siemens Biograph mMR positron emission tomography (PET)/ magnetic resonance imaging (MRI) 3 Tesla scanner. The PET allows us to see the changes in the "reward signals" - dopamine - in the brain using a radioactive dye called [11C]Raclopride. The MRI, on the other hand, enables us to take detailed pictures of the brain activities during cognitive tasks using a high-powered magnet. Reviewing these pictures will help us understand the influence of caffeine on reward signals and brain activities during the learning process.
Read the detailed description
Adenosine 2A receptors (A2AR) colocalize with and exerts allosteric antagonism to dopamine D2 receptors (D2R) by co-forming functional heterodimers in the striatum. Preliminary studies using positron emission tomography (PET) with [11C]Raclopride have shown increased D2/D3R availability by A2AR antagonism with caffeine and decreased D2/D3R availability by enhanced adenosine signaling during sleep deprivation, supporting the notion of A2AR-D2R interactions in vivo. However, how A2AR-D2R interactions contribute to D2R-mediated neurocognitive functions is scarcely investigated.
Reinforcement learning, a dopamine-mediated cognitive process crucially involved in various human behaviors including habit, preference, belief, and resistance to change, is often found altered in dopamine-associated disorders. For instance, hyper-dopaminergic function in the striatum, as observed in psychosis, leads to a reduction in reward learning and a blunted task-related neural activity. Through the antagonistic effect of A2AR on D2R signaling, blocking A2AR can potentially enhance D2R-mediated negative reinforcement, a.k.a. a "no-go" response. In rodents, A2AR agonists diminish reinforcement of psychostimulants, while an A2AR antagonist can facilitate reward-seeking effects of reinforcers. Hence, in this double-blind randomized crossover study, the investigators aim to use caffeine, an adenosine antagonist as well as a commonly used psychostimulant by nearly 80% of the worldwide population, to examine whether blocking A2AR will enhance D2R-modulated reinforcement learning/no-go responses through modulating D2R signaling pharmacologically.
The long-term goal of this study is to further the understanding of molecular mechanisms related to A2AR-D2R heterodimers and the clinical potential of modulating A2AR-D2R interactions. Twelve young healthy non-smokers will enroll in this study. Each participant will undergo a caffeine and a placebo condition. In each condition, participants will first go through a 6-day ambulatory washout period where participants will be asked to abstain from caffeinated dietary, alcohol, and drugs, and stay in regular bed- and wakeup time. On day 7, a PET/fMRI scan will take place at noon, and a caffeine or placebo tablet will be administered orally 20 mins prior to the scan.
Simultaneous PET/fMRI will be used to examine the association between the neurochemical changes (i.e., D2/D3R availability as quantified by [11C]Raclopride) and the hemodynamic responses (i.e., task-related blood oxygen level-dependent fMRI activity) during reinforcement learning in the caffeine condition compared to placebo. It is hypothesized that enhanced D2/D3R availability mediates the facilitating effect of caffeine on reinforcement learning. Specifically, the investigators expect that caffeine will enhance fMRI responses in reward-related brain regions, and that the increased fMRI response will positively correlate with a change in D2/D3R availability.
- Conditions
- Healthy, Caffeine, Adenosine, Dopamine D2/3 Receptor Availability
- Being tested
- Caffeine (200 mg), Placebo
- Keywords
- PET/fMRI
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Caffeine (200 mg)Drug
Caffeine (200mg) will be administered per os 20 minutes prior to the PET/fMRI data acquisition.
PlaceboDrug
Also called Lactose
Lactose tablet will be administered per os 20 minutes prior to the PET/fMRI data acquisition.
| Study group | Role | What they receive |
|---|---|---|
| Caffeine | Experimental | Caffeine tablet, 200mg Receives: Drug: Caffeine (200 mg) |
| Placebo | Placebo comparator | Lactose tablet Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Dopamine D2/D3 receptor availability
Dopamine D2/D3 receptor availability will be measured and indexed by the [11C]Raclopride nondisplaceable binding potential (BPND).
Measured: During the PET/fMRI scan on the study day
Effects of caffeine on reinforcement learning assessed by Probabilistic Selection Task (PST) in fMRI
Reinforcement learning and the associated brain activity will be measured using PST in a fMRI scan. The reinforcement learning is indexed by the accuracy of the task performance on the behavioral level and the hemodynamic response to reward feedback on the neural level.
Measured: During the PET/fMRI scan on the study day
Secondary outcomes (2)
Effects of caffeine on motor inhibition assessed by a Go/NoGo task in fMRI
Motor inhibition and the associated brain activity will be examined using Go/NoGo in a fMRI scan. The reinforcement learning is indexed by the accuracy of the task performance on the behavioral level and the hemodynamic response during the inhibition of motor reactions on the neural level.
Measured: During the PET/fMRI scan on the study day
Effects of caffeine on salience measured by Salience Attribution Test (SAT)
Participants' salience to reward stimuli linked to the Probabilistic Selection Task will be assessed using Salience Attribution Test. In the task, participants will use a visual analogue scale to indicate their estimation of the reward probability (0 to 100%) of each stimulus they have learned in the task during the scan. The salience will be indicated by the difference between their estimation and the real probability, as well as the contrast between high and low probability in estimation and in reality.
Measured: After the PET/fMRI scan on the study day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 Jan 2025
- Study start17 May 2023
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for HealthyStudies of the same condition, open and under way.
- 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 4
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 12 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Hsiao-Ying Wey
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Hsiao-Ying Wey, Martinos Center for Biomedical Imaging
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06763172
- Sponsor's protocol ID
- IRB2022P001681
- Other IDs
- 1R21MH138923-01
- Acronym
- Caffeine-RAC
- Status last verified
- Jan 2025
- First submitted
- 31 Dec 2024
- Last updated
- 9 Jan 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Raw, subject-level data files will be submitted to NIMH Data Archive (NDA). These include \[11C\]Raclopride PET data as well as behavioral and fMRI data from Probabilistic Selection Tasks and Go/Nogo tasks. Other behavioral data e.g. Salience Attribution Tests, Karolinska Sleepiness Scale, and State-Trait Anxiety Inventory, as well as fMRI data e.g. Arterial Spin Labeling and resting state fMRI will also be included. Relevant resources, such as code used for data processing and analyses, will be made publicly available through GitHub. The main readme.md file for the project will include instructions and parameter choices to execute the codes/scripts. Code documentation will include instructions on how to access data, the name and email address of a contact person for questions, and relevant references to publications. To ensure long-term accessibility, a copy of the GitHub code repository will be archived in Zenodo at the time of publication with a digital object identifier (DOI).
Publications
Bedingfield JB, King DA, Holloway FA. Cocaine and caffeine: conditioned place preference, locomotor activity, and additivity. Pharmacol Biochem Behav. 1998 Nov;61(3):291-6. doi: 10.1016/s0091-3057(98)00092-6.
PubMed 9768563Moran EK, Culbreth AJ, Kandala S, Barch DM. From neuroimaging to daily functioning: A multimethod analysis of reward anticipation in people with schizophrenia. J Abnorm Psychol. 2019 Oct;128(7):723-734. doi: 10.1037/abn0000461. Epub 2019 Aug 29.
PubMed 31464449Volkow ND, Wang GJ, Telang F, Fowler JS, Logan J, Wong C, Ma J, Pradhan K, Tomasi D, Thanos PK, Ferre S, Jayne M. Sleep deprivation decreases binding of [11C]raclopride to dopamine D2/D3 receptors in the human brain. J Neurosci. 2008 Aug 20;28(34):8454-61. doi: 10.1523/JNEUROSCI.1443-08.2008.
PubMed 18716203Kaasinen V, Aalto S, Nagren K, Rinne JO. Dopaminergic effects of caffeine in the human striatum and thalamus. Neuroreport. 2004 Feb 9;15(2):281-5. doi: 10.1097/00001756-200402090-00014.
PubMed 15076753Volkow ND, Wang GJ, Logan J, Alexoff D, Fowler JS, Thanos PK, Wong C, Casado V, Ferre S, Tomasi D. Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain. Transl Psychiatry. 2015 Apr 14;5(4):e549. doi: 10.1038/tp.2015.46.
PubMed 25871974Ferre S, Bonaventura J, Tomasi D, Navarro G, Moreno E, Cortes A, Lluis C, Casado V, Volkow ND. Allosteric mechanisms within the adenosine A2A-dopamine D2 receptor heterotetramer. Neuropharmacology. 2016 May;104:154-60. doi: 10.1016/j.neuropharm.2015.05.028. Epub 2015 Jun 4.
PubMed 26051403
Study at a glance
From the registry record, last updated by the sponsor on 9 Jan 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Measure Striatal Adenosine-dopamine Receptors Interactions: from Molecule to Behaviors
- ClinicalTrials.gov ID
- NCT06763172
- Acronym / sponsor ID
- Caffeine-RAC / IRB2022P001681
- Conditions
- Healthy, Caffeine, Adenosine, Dopamine D2/3 Receptor Availability
- Keywords
- PET/fMRI
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 12 participants (estimated)
- Lead sponsor
- Hsiao-Ying WeyUniversity, hospital or other
- Study start
- 17 May 2023 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 8 Jan 2025 (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.
This research study aims to determine whether and how caffeine intake affects learning process through reward feedback compared to placebo. The data acquired from this study would improve our understanding on the consequence and mechanism of caffeine intake in the aspect of learning process.
Participants will perform a reinforcement learning task (i.e. Probabilistic Selection Task) and a motor inhibition task (i.e. Go/NoGo task) in a brain scan. The scan will be done with the Siemens Biograph mMR positron emission tomography (PET)/ magnetic resonance imaging (MRI) 3 Tesla scanner. The PET allows us to see the changes in the "reward signals" - dopamine - in the brain using a radioactive dye called [11C]Raclopride. The MRI, on the other hand, enables us to take detailed pictures of the brain activities during cognitive tasks using a high-powered magnet. Reviewing these pictures will help us understand the influence of caffeine on reward signals and brain activities during the learning process.
Detailed description
Adenosine 2A receptors (A2AR) colocalize with and exerts allosteric antagonism to dopamine D2 receptors (D2R) by co-forming functional heterodimers in the striatum. Preliminary studies using positron emission tomography (PET) with [11C]Raclopride have shown increased D2/D3R availability by A2AR antagonism with caffeine and decreased D2/D3R availability by enhanced adenosine signaling during sleep deprivation, supporting the notion of A2AR-D2R interactions in vivo. However, how A2AR-D2R interactions contribute to D2R-mediated neurocognitive functions is scarcely investigated.
Reinforcement learning, a dopamine-mediated cognitive process crucially involved in various human behaviors including habit, preference, belief, and resistance to change, is often found altered in dopamine-associated disorders. For instance, hyper-dopaminergic function in the striatum, as observed in psychosis, leads to a reduction in reward learning and a blunted task-related neural activity. Through the antagonistic effect of A2AR on D2R signaling, blocking A2AR can potentially enhance D2R-mediated negative reinforcement, a.k.a. a "no-go" response. In rodents, A2AR agonists diminish reinforcement of psychostimulants, while an A2AR antagonist can facilitate reward-seeking effects of reinforcers. Hence, in this double-blind randomized crossover study, the investigators aim to use caffeine, an adenosine antagonist as well as a commonly used psychostimulant by nearly 80% of the worldwide population, to examine whether blocking A2AR will enhance D2R-modulated reinforcement learning/no-go responses through modulating D2R signaling pharmacologically.
The long-term goal of this study is to further the understanding of molecular mechanisms related to A2AR-D2R heterodimers and the clinical potential of modulating A2AR-D2R interactions. Twelve young healthy non-smokers will enroll in this study. Each participant will undergo a caffeine and a placebo condition. In each condition, participants will first go through a 6-day ambulatory washout period where participants will be asked to abstain from caffeinated dietary, alcohol, and drugs, and stay in regular bed- and wakeup time. On day 7, a PET/fMRI scan will take place at noon, and a caffeine or placebo tablet will be administered orally 20 mins prior to the scan.
Simultaneous PET/fMRI will be used to examine the association between the neurochemical changes (i.e., D2/D3R availability as quantified by [11C]Raclopride) and the hemodynamic responses (i.e., task-related blood oxygen level-dependent fMRI activity) during reinforcement learning in the caffeine condition compared to placebo. It is hypothesized that enhanced D2/D3R availability mediates the facilitating effect of caffeine on reinforcement learning. Specifically, the investigators expect that caffeine will enhance fMRI responses in reward-related brain regions, and that the increased fMRI response will positively correlate with a change in D2/D3R availability.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Caffeine | Experimental | Drug: Caffeine (200 mg)Caffeine tablet, 200mg |
| Placebo | Placebo comparator | Drug: PlaceboLactose tablet |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Age ≥ 18 and ≤ 45.
- Habitual caffeine intake ≥ 100 mg and ≤ 450 mg daily.
- Non-smokers.
- Clinically healthy.
- Have normal vision or corrected to normal vision.
Key exclusion criteria (18 listed)
- Pregnant or lactating women.
- Women using hormonal contraceptives.
- BMI < 18.5 or > 29.9
- Sleep disturbance or extreme chronotype.
- Urine test positive on one of the following substances: benzoylecgonine, morphine, d-Methamphetamine, d-Amphetamine, Benzodiazepines, Secobarbital, Methadone, Buprenorphine Glucuronide, Nortriptyline, MDMA, Oxycodone, PCP, Propoxyphene, and Cannabis/THC
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 |
|---|---|---|
| Caffeine (200 mg)Caffeine (200mg) will be administered per os 20 minutes prior to the PET/fMRI data acquisition. | Drug | Caffeine |
| PlaceboAlso: LactoseLactose tablet will be administered per os 20 minutes prior to the PET/fMRI data acquisition. | Drug | Placebo |
Primary outcome
Dopamine D2/D3 receptor availability
Time frame: During the PET/fMRI scan on the study day
Dopamine D2/D3 receptor availability will be measured and indexed by the [11C]Raclopride nondisplaceable binding potential (BPND).
Effects of caffeine on reinforcement learning assessed by Probabilistic Selection Task (PST) in fMRI
Time frame: During the PET/fMRI scan on the study day
Reinforcement learning and the associated brain activity will be measured using PST in a fMRI scan. The reinforcement learning is indexed by the accuracy of the task performance on the behavioral level and the hemodynamic response to reward feedback on the neural level.
2 secondary outcomes
Effects of caffeine on motor inhibition assessed by a Go/NoGo task in fMRI
Time frame: During the PET/fMRI scan on the study day
Effects of caffeine on salience measured by Salience Attribution Test (SAT)
Time frame: After the PET/fMRI scan on the study day
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 9 Jan 2025.
- Background: PubMed 9768563Bedingfield JB, King DA, Holloway FA. Cocaine and caffeine: conditioned place preference, locomotor activity, and additivity. Pharmacol Biochem Behav. 1998 Nov;61(3):291-6. doi: 10.1016/s0091-3057(98)00092-6.
- Background: PubMed 31464449Moran EK, Culbreth AJ, Kandala S, Barch DM. From neuroimaging to daily functioning: A multimethod analysis of reward anticipation in people with schizophrenia. J Abnorm Psychol. 2019 Oct;128(7):723-734. doi: 10.1037/abn0000461. Epub 2019 Aug 29.
- Background: PubMed 18716203Volkow ND, Wang GJ, Telang F, Fowler JS, Logan J, Wong C, Ma J, Pradhan K, Tomasi D, Thanos PK, Ferre S, Jayne M. Sleep deprivation decreases binding of [11C]raclopride to dopamine D2/D3 receptors in the human brain. J Neurosci. 2008 Aug 20;28(34):8454-61. doi: 10.1523/JNEUROSCI.1443-08.2008.
- Background: PubMed 15076753Kaasinen V, Aalto S, Nagren K, Rinne JO. Dopaminergic effects of caffeine in the human striatum and thalamus. Neuroreport. 2004 Feb 9;15(2):281-5. doi: 10.1097/00001756-200402090-00014.
- Background: PubMed 25871974Volkow ND, Wang GJ, Logan J, Alexoff D, Fowler JS, Thanos PK, Wong C, Casado V, Ferre S, Tomasi D. Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain. Transl Psychiatry. 2015 Apr 14;5(4):e549. doi: 10.1038/tp.2015.46.
- Background: PubMed 26051403Ferre S, Bonaventura J, Tomasi D, Navarro G, Moreno E, Cortes A, Lluis C, Casado V, Volkow ND. Allosteric mechanisms within the adenosine A2A-dopamine D2 receptor heterotetramer. Neuropharmacology. 2016 May;104:154-60. doi: 10.1016/j.neuropharm.2015.05.028. Epub 2015 Jun 4.
- Individual participant dataSharing planned: Yes. Raw, subject-level data files will be submitted to NIMH Data Archive (NDA). These include [11C]Raclopride PET data as well as behavioral and fMRI data from Probabilistic Selection Tasks and Go/Nogo tasks. Other behavioral data e.g. Salience Attribution Tests, Karolinska Sleepiness Scale, and State-Trait Anxiety Inventory, as well as fMRI data e.g. Arterial Spin Labeling and resting state fMRI will also be included. Relevant resources, such as code used for data processing and analyses, will be made publicly available through GitHub. The main readme.md file for the project will include instructions and parameter choices to execute the codes/scripts. Code documentation will include instructions on how to access data, the name and email address of a contact person for questions, and relevant references to publications. To ensure long-term accessibility, a copy of the GitHub code repository will be archived in Zenodo at the time of publication with a digital object identifier (DOI).
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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.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Caffeine (200 mg) in people with Healthy and Caffeine, run by Hsiao-Ying Wey 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 5 inclusion and 18 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: looking for participants now, as of the sponsor's last update on 9 Jan 2025. 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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 Hsiao-Ying Wey, PhD (6177241384, hsiaoying.wey@mgh.harvard.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Dopamine D2/D3 receptor availability (time frame: During the PET/fMRI scan on the study day). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06763172, which also lists 6 linked publications.
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 9 Jan 2025.