CaffeineADoReNCT05325502
Does Caffeine Facilitate Human Reward Learning Behaviors?
A study testing caffeine and mannitol in people with Caffeine, run by Yu-Shiuan Lin at 1 site in Switzerland.
Trial summary
"Learning from the rewards" is underlying the formulation of knowledge and habits in daily life. Caffeine is the most commonly used "psychoactive" substance that could change one's mind state by affecting the brain and nervous system. By such effects, caffeine enhances reward signals - dopamine - in human brains. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Caffeine
- What is being tested?
- caffeine and mannitol
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 36 participants
- Where
- 1 siteSwitzerland
- Study dates
- 5 May 2022to 31 Dec 2026
- 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 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age ≥ 18 and ≤ 40
- Clinically healthy
- Non-smokers
Who cannot join
- Habitual caffeine intake < 100 mg or > 450 mg
- Pregnant or lactating women
- Women using hormonal contraceptives
- BMI < 18.5 or > 29.9
- Sleep disturbance or extreme chronotypes
- Nicotine or recreational drug users
Show all 13Show fewer
- Depression, anxiety, psychosis, or neurologic disorders
- Severe heart or cardiovascular diseases
- Diabetes or metabolic diseases
- Under chronic medications
- Incapable to operate the tasks or comprehend the study information in German or English
- Users of the Bopomo alphates utilized as stimuli in the reward learning tasks
- Current enrolment in other clinical trials
Trial locations and contacts
1 site in 1 country.
Switzerland1 site
Centre for Chronobiology, University Psychiatric Clinics Basel
Basel, Canton of Basel-City, CH-4002
About this study
Official title: Caffeine and Reward Learning: Characterizing Behavioral Expression of Adenosine-Dopamine Interaction
"Learning from the rewards" is underlying the formulation of knowledge and habits in daily life. Caffeine is the most commonly used "psychoactive" substance that could change one's mind state by affecting the brain and nervous system. By such effects, caffeine enhances reward signals - dopamine - in human brains. In this research study, we will find out whether taking caffeine acutely or daily can enhance reward learning processes.
Read the detailed description
Reward learning is associated with the formulation of habits, memories, and beliefs. Positive (receiving an unexpected reward) and negative reinforcement (eliminating an unwanted state) learning are primarily modulated by striatal dopamine D1 and D2 receptors. While caffeine, a psychostimulant regularly consumed by 80% worldwide population, is known to facilitate striatal dopamine signaling, the potential of caffeine on enhancing reward learning in humans remains unknown.
In this double-blind, randomized, crossover study, 36 young healthy non-smoking habitual caffeine consumers (daily dose 100 - 450 mg) who are aged between 18 and 40 will be examined. Each of the 36 participants (18 F, 18 M) will undergo an acute caffeine condition, a daily caffeine condition, and a daily placebo condition. Each condition consists of 7 days - 6 ambulatory days followed by 1 laboratory visit.
In the ambulatory part, participants will abstain from caffeine, nicotine, medications, and recreational drugs. Compliance to the interventions and abstinence of caffeine will be monitored by salivary caffeine concentration every day. Bedtime and sleep quality will be recorded in sleep diary. On the laboratory visit, participants will perform cognitive tasks on a 2.5h task battery, which includes a probabilistic selection task, a motor inhibition task, and a salience attribution test. We also measure their arousal and anxiety levels 1h after the second intake on the laboratory visit.
We will use Bayes factor analyses to test our confirmatory hypotheses (on the primary outcomes): 1) Caffeine enhances the accuracy of reward learning; 2) Daily intake of caffeine facilitates the negative reinforcement compared to acute its intake. On the secondary outcomes, we examine the exploratory hypotheses that caffeine enhances motor inhibition and motivational salience. Arousal and anxiety levels will be examined as a covariate which potentially contribute to the caffeine-induced changes in reward learning performance.
- Conditions
- Caffeine
- Being tested
- caffeine, mannitol
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
caffeineDietary supplement
two doses per day: 200 mg caffeine in the morning; 100 mg caffeine in the afternoon
mannitolDietary supplement
two doses per day: 200 mg in the morning \& 100 mg in the afternoon
| Study group | Role | What they receive |
|---|---|---|
| Placebo | Placebo comparator | 7 days placebo intake. Receives: Dietary Supplement: mannitol |
| Acute caffeine | Active comparator | 6 days placebo followed by 1 day caffeine intake. Receives: Dietary Supplement: caffeine; Dietary Supplement: mannitol |
| Daily caffeine | Experimental | 7 days caffeine intake Receives: Dietary Supplement: caffeine |
What is being measured
The primary outcome is the main question the study is designed to answer.
The accuracy (% of correct answers) in implicit learning through different probabilities of monetary reward feedback
Through a probabilistic selection task, participant will go through a training phase to learn the rules which options may be more likely to return monetary feedback, and the knowledge learned will be tested in a second phase where the task difficulty is increased, and no feedback is provided. The overall accuracy in the testing phases will be examined, as well as the accuracies in choosing or avoiding the highest and lowest reward-probability stimuli.
Measured: 1-hour after the second intake on the 7th day
Secondary outcomes (2)
The errors in motor inhibition (rates of false alarm) in a motor inhibition task
Through a reaction-inhibition task (Go/NoGo), participants will go through two phases of the task: 1) Only respond to a specific stimulus when it shows; 2) Respond to all stimuli except for the specific stimulus. The accuracy in motor inhibition will be indicated by the errors made in the no-go signals (i.e. false alarm).
Measured: 1.5-hour after the second intake on the 7th day
Salience attribution behaviors
subjective perception towards the probabilities (0 -100%) of reward feedback from each choice in the probabilistic selection task.
Measured: 1.5-hour after the second intake on the 7th day
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Apr 2022
- Study start5 May 2022
- Primary completion31 Dec 2025
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CaffeineStudies 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 N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 36 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Yu-Shiuan Lin
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Yu-Shiuan Lin, Centre for Chronobiology
- Investigators
- Yu-Shiuan Lin, PhD, Principal investigator, Centre for Chronobiology, University Psychiatric Clinics Basel
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05325502
- Sponsor's protocol ID
- CChronobiology
- Acronym
- ADoRe
- Status last verified
- Mar 2026
- First submitted
- 28 Mar 2022
- Last updated
- 17 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: IPD data, including SAP, CSR, and analytic codes, will be made available on OSF or provided upon requests after the data requested are published.
Study at a glance
From the registry record, last updated by the sponsor on 17 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Caffeine and Reward Learning: Characterizing Behavioral Expression of Adenosine-Dopamine Interaction
- ClinicalTrials.gov ID
- NCT05325502
- Acronym / sponsor ID
- ADoRe / CChronobiology
- Conditions
- Caffeine
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 36 participants (estimated)
- Lead sponsor
- Yu-Shiuan LinUniversity, hospital or other
- Study start
- 5 May 2022 (actual)
- Primary completion
- 31 Dec 2025 (actual)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 13 Apr 2022 (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.
"Learning from the rewards" is underlying the formulation of knowledge and habits in daily life. Caffeine is the most commonly used "psychoactive" substance that could change one's mind state by affecting the brain and nervous system. By such effects, caffeine enhances reward signals - dopamine - in human brains. In this research study, we will find out whether taking caffeine acutely or daily can enhance reward learning processes.
Detailed description
Reward learning is associated with the formulation of habits, memories, and beliefs. Positive (receiving an unexpected reward) and negative reinforcement (eliminating an unwanted state) learning are primarily modulated by striatal dopamine D1 and D2 receptors. While caffeine, a psychostimulant regularly consumed by 80% worldwide population, is known to facilitate striatal dopamine signaling, the potential of caffeine on enhancing reward learning in humans remains unknown.
In this double-blind, randomized, crossover study, 36 young healthy non-smoking habitual caffeine consumers (daily dose 100 - 450 mg) who are aged between 18 and 40 will be examined. Each of the 36 participants (18 F, 18 M) will undergo an acute caffeine condition, a daily caffeine condition, and a daily placebo condition. Each condition consists of 7 days - 6 ambulatory days followed by 1 laboratory visit.
In the ambulatory part, participants will abstain from caffeine, nicotine, medications, and recreational drugs. Compliance to the interventions and abstinence of caffeine will be monitored by salivary caffeine concentration every day. Bedtime and sleep quality will be recorded in sleep diary. On the laboratory visit, participants will perform cognitive tasks on a 2.5h task battery, which includes a probabilistic selection task, a motor inhibition task, and a salience attribution test. We also measure their arousal and anxiety levels 1h after the second intake on the laboratory visit.
We will use Bayes factor analyses to test our confirmatory hypotheses (on the primary outcomes): 1) Caffeine enhances the accuracy of reward learning; 2) Daily intake of caffeine facilitates the negative reinforcement compared to acute its intake. On the secondary outcomes, we examine the exploratory hypotheses that caffeine enhances motor inhibition and motivational salience. Arousal and anxiety levels will be examined as a covariate which potentially contribute to the caffeine-induced changes in reward learning performance.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Placebo | Placebo comparator | Dietary Supplement: mannitol7 days placebo intake. |
| Acute caffeine | Active comparator | Dietary Supplement: caffeine, Dietary Supplement: mannitol6 days placebo followed by 1 day caffeine intake. |
| Daily caffeine | Experimental | Dietary Supplement: caffeine7 days caffeine intake |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Age ≥ 18 and ≤ 40
- Clinically healthy
- Non-smokers
Key exclusion criteria (13 listed)
- Habitual caffeine intake < 100 mg or > 450 mg
- Pregnant or lactating women
- Women using hormonal contraceptives
- BMI < 18.5 or > 29.9
- Sleep disturbance or extreme chronotypes
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 |
|---|---|---|
| caffeinetwo doses per day: 200 mg caffeine in the morning; 100 mg caffeine in the afternoon | Dietary supplement | Acute caffeine, Daily caffeine |
| mannitoltwo doses per day: 200 mg in the morning \& 100 mg in the afternoon | Dietary supplement | Acute caffeine, Placebo |
Primary outcome
The accuracy (% of correct answers) in implicit learning through different probabilities of monetary reward feedback
Time frame: 1-hour after the second intake on the 7th day
Through a probabilistic selection task, participant will go through a training phase to learn the rules which options may be more likely to return monetary feedback, and the knowledge learned will be tested in a second phase where the task difficulty is increased, and no feedback is provided. The overall accuracy in the testing phases will be examined, as well as the accuracies in choosing or avoiding the highest and lowest reward-probability stimuli.
2 secondary outcomes
The errors in motor inhibition (rates of false alarm) in a motor inhibition task
Time frame: 1.5-hour after the second intake on the 7th day
Salience attribution behaviors
Time frame: 1.5-hour after the second intake on the 7th 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 17 Mar 2026.
- Individual participant dataSharing planned: Yes. IPD data, including SAP, CSR, and analytic codes, will be made available on OSF or provided upon requests after the data requested are published.
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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. This study is not recruiting at the moment.
Yu-Shiuan Lin, PhD principal investigator
Centre for Chronobiology, University Psychiatric Clinics Basel
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing caffeine and mannitol in people with Caffeine, run by Yu-Shiuan Lin at 1 site in Switzerland.
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 3 inclusion and 13 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: under way, not looking for participants, as of the sponsor's last update on 17 Mar 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 Switzerland. 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.
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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The accuracy (% of correct answers) in implicit learning through different probabilities of monetary reward feedback (time frame: 1-hour after the second intake on the 7th day). 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 17 Mar 2026.