A study of the nocebo effect of caffeine: differences in expression with and without explanation and interindividual variability factors.

A study of the nocebo effect of caffeine: differences in expression with and without explanation and interindividual variability factors. - A study of the nocebo effect of caffeine

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

JPRN

Registry ID

JPRN-UMIN000047526

Enrollment

150

Registered

2022-04-19

Start date

2022-09-01

Completion date

Unknown

Last updated

2026-06-29

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Adverse effect

Interventions

Groups with and without explanation of caffeine side effects, etc.

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: # Healthy adults aged 20-39 # Able to drink black coffee # Able to maintain confidentiality of information related to this study.

Exclusion criteria

Exclusion criteria: # Persons who have a history of getting sick from caffeinated beverages. # Persons taking drugs (xanthines, CNS stimulants, MAO inhibitors, cimetidine, etc.) that are listed as concomitant precautions in the caffeine package insert (caffeine anhydrous). # Those taking mucoprotective or gastric acid secretion inhibitors (including medical and OTC drugs) # Women who are pregnant or may become pregnant # Smokers or non-smokers #Those with a history of adverse drug reactions or allergies to medications (however, the decision to participate in the study will be made after consultation with a medical specialist). # Other persons who are considered inappropriate to conduct this study.

Design outcomes

Primary

Measure	Time frame
To compare the subjective indicators of caffeine (subjective symptom questionnaire and state anxiety) in the different manifestations of the nocebo effect. To compare palpitations and gastric discomfort (VAS) and STAI (state anxiety) as subjective measures before and after coffee consumption in the explained and unexplained groups.	—

Secondary

Measure	Time frame
To measure changes in cerebral blood flow in the dorsolateral prefrontal cortex of the brain with respect to the perception of the nocebo effect. Furthermore, we will elucidate the inter-individual variability factors of the nocebo effect and examine the differences in the onset of the nocebo effect and the mechanism of its onset. The COMT gene polymorphism, 5-HTT gene polymorphism, CCK gene polymorphism differences and personality will be examined as interindividual variability factors for the nocebo effect.	—

Measure

Time frame

To measure changes in cerebral blood flow in the dorsolateral prefrontal cortex of the brain with respect to the perception of the nocebo effect. Furthermore, we will elucidate the inter-individual variability factors of the nocebo effect and examine the differences in the onset of the nocebo effect and the mechanism of its onset. The COMT gene polymorphism, 5-HTT gene polymorphism, CCK gene polymorphism differences and personality will be examined as interindividual variability factors for the nocebo effect.

—

Countries

Japan

Contacts

Public ContactMinae Isawa

Keio University, Faculty of Pharmacy Clinical Pharmacy

isawa-mn@pha.keio.ac.jp03-5400-2486

Outcome results

None listed

Source: JPRN (via WHO ICTRP) · Data processed: Jul 3, 2026