Does Caffeine Facilitate Human Reward Learning Behaviors? (ADoRe)

March 16, 2026 updated by: Yu-Shiuan Lin

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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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 Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
36

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Switzerland
    • Canton of Basel-City
      • Basel, Canton of Basel-City, Switzerland, CH-4002
        • Centre for Chronobiology, University Psychiatric Clinics Basel

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

14 years to 36 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age ≥ 18 and ≤ 40
  • Clinically healthy
  • Non-smokers

Exclusion Criteria:

  • 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
  • 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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Placebo Comparator: Placebo
7 days placebo intake.
Dietary supplement: mannitol
two doses per day: 200 mg in the morning & 100 mg in the afternoon
Active Comparator: Acute caffeine
6 days placebo followed by 1 day caffeine intake.
Dietary supplement: mannitol
two doses per day: 200 mg in the morning & 100 mg in the afternoon
Dietary supplement: caffeine
two doses per day: 200 mg caffeine in the morning; 100 mg caffeine in the afternoon
Experimental: Daily caffeine
7 days caffeine intake
Dietary supplement: caffeine
two doses per day: 200 mg caffeine in the morning; 100 mg caffeine in the afternoon

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
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.
1-hour after the second intake on the 7th day

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
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
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).
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
subjective perception towards the probabilities (0 -100%) of reward feedback from each choice in the probabilistic selection task.
1.5-hour after the second intake on the 7th day

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Self-report anxiety levels
Time Frame: 1-hour after the second intake on the 7th day
State-Trait Anxiety Inventory for Adults (STAI-A) is used to examine the subjective anxiety levels in general as a trait (20 questions) and as a current state (20 questions). Participants will rate the levels using a Likert's scale (For trait - 0: Almost never, 1: Sometimes, 2: Often, 3: Almost always; For current state - 0: not at all, 1: Somewhat, 2: Moderately so, 3: Very much so).
1-hour after the second intake on the 7th day
Subjective sleepiness and alertness
Time Frame: 1-hour after the second intake on the 7th day
Self-report one-question Karolinska Sleepiness Scale is used to rate the subjective sleepiness/alertness from 1 (very awake), 3 (awake), 5 (neither awake or tired), 7 (tired but no problem to stay awake), to 9 (very tired, big problem to stay awake, struggling with sleep), and 2, 4, 6, 8 for intermediate levels.
1-hour after the second intake on the 7th day
heart rate measurement
Time Frame: 1-hour after the second intake on the 7th day
heart rates (per min)
1-hour after the second intake on the 7th day
blood pressure measurement
Time Frame: 1-hour after the second intake on the 7th day
systolic and diastolic blood pressure
1-hour after the second intake on the 7th day

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Yu-Shiuan Lin

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Yu-Shiuan Lin, PhD, Centre for Chronobiology, University Psychiatric Clinics Basel

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 5, 2022

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2025

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 28, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 12, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 13, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • CChronobiology

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

IPD data, including SAP, CSR, and analytic codes, will be made available on OSF or provided upon requests after the data requested are published.

IPD Sharing Time Frame

Data will be made available after publishing (estimated to be July 2023).

IPD Sharing Access Criteria

Researchers who are interested in using IPD data from ADoRe can either contact the Sponsor-Investigator (ys.lin@unibas.ch, Yu-Shiuan Lin, PhD) or access from ADoRe project on OSF (https://osf.io/wzf2y/). Please note that the data folder of this project will be only accessible after publishing.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ANALYTIC_CODE
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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