RecruitingPhase 4

Effects of Caffeine on Reinforcement Learning in Healthy Adults Using PET/MRI

United States12 participantsStarted 2023-05-17

Plain-language 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. 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.

Who can participate

Age range

18 Years – 45 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: * 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. Exclusion Criteria: * 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. * 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…

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Dopamine D2/D3 receptor availability

Timeframe: During the PET/fMRI scan on the study day

Effects of caffeine on reinforcement learning assessed by Probabilistic Selection Task (PST) in fMRI

Timeframe: During the PET/fMRI scan on the study day

Trial details

NCT IDNCT06763172

SponsorHsiao-Ying Wey

Sponsor typeOTHER

Study typeINTERVENTIONAL

Primary completion2026-12-31

Contact for this trial

Hsiao-Ying Wey, PhD

6177241384 hsiaoying.wey@mgh.harvard.edu

View on ClinicalTrials.gov More Healthy trials