Skip to main content
OpenTrials
Completed

NCT Number: NCT05866848

Effects of Caffeine on Cerebral Blood Flow

The goal of this clinical trial is to evaluate in clinically healthy young people if:

* after caffeine ingestion, there are variations in blood velocity of the middle cerebral arteries (VMCA), * this variation is dependent on the administered dose.

Transcranial Doppler ultrasonography was used to record blood VMCA in three groups of 15 clinically healthy young adults each - no caffeine, low caffeine (45 mg) and high caffeine group (120 mg). Transcranial Doppler ultrasonography provided simultaneous bilateral VMCA measurements while subjects performed functional tests (hyperventilation and hypoventilation orders) and three cognitive activities (Test 1, short-term remembering, Test 2, solving a vocabulary problem, and Test 3, solving a math problem) each in 31-second tests with 1-minute rest between them. Participants were assessed before and 30 minutes after caffeine ingestion.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Cardiovascular System

Age range

18 year–30 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Coimbra Health School

Coimbra, 3046-854, Portugal

About this study

Were used in the study, Capsules dosed with 45mg and 120 mg of anhydrous caffeine and flour capsules as a placebo. In the preparation of the capsules, a semi-automatic capsulator No. 0 (Capsunorm® by Tecnyfarma®) were used, colorless hard gelatin capsules No. 0 by Acopharma® and anhydrous caffeine (Biochem®, C.A.S. 58-08-2).

Viasys Sonara transcranial Doppler unit and a 2 MHz probe were used to sample the middle cerebral artery at depths of 60 millimeters, using emission doppler pulsed performing spectral analysis in real time. Two probes (bilaterally) of 2MHz were placed at a depth between 55 and 60 mm, thus making it possible to analyse both middle cerebral arteries simultaneously.

Each participant was asked not to ingest caffeine and exercise vigorously for at least 12 hours before the assessment. In the case of smokers, they were also asked not to smoke for at least 2 hours before the evaluation. The laboratory had medium luminosity, silent and controlled temperature (23º/24ºC). To avoid inter-observer errors, all examinations were performed by the same investigator who was not aware of what dose was/had been administered to the participant.

Subjects were tested while seated in a reclining chair located in a dimly lit, sound-attenuated room and performed the activities with their eyes closed.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • clinically healthy young people

Exclusion criteria

  • Individuals with hypertension, high cholesterol, diabetes, arrhythmias, carotid sinus syndrome, severe carotid stenosis and who were in an unstable clinical situation.

Treatment and study plan

Placebo

Other

Flour capsules as a placebo.

Anhydrous caffeine (45mg)

Other

Capsules dosed with 45mg of anhydrous caffeine.

Anhydrous caffeine (120mg)

Other

Capsules dosed with 120mg of anhydrous caffeine.

Primary outcomes

  1. Changes in Mean Velocity (Basal)

    Time frame: 30 minutes

    Changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  2. Changes in Mean Velocity (Hypoventilation)

    Time frame: 30 minutes

    By performing Hypoventilation, changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  3. Changes in Mean Velocity (Hyperventilation)

    Time frame: 30 minutes

    By performing Hyperventilation, changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  4. Changes in Mean Velocity (Short-term memory test)

    Time frame: 30 minutes

    With short-term memory test, changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  5. Changes in Mean Velocity (Vocabulary problem)

    Time frame: 30 minutes

    With solving vocabulary problems, changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  6. Changes in Mean Velocity (Math problem.)

    Time frame: 30 minutes

    With solving math problems, changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  7. Changes in Peak systolic velocity (Basal)

    Time frame: 30 minutes

    Changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  8. Changes in Peak systolic velocity (Hypoventilation)

    Time frame: 30 minutes

    By performing Hypoventilation, changes in Peak systolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  9. Changes in Peak systolic velocity (Hyperventilation)

    Time frame: 30 minutes

    By performing Hyperventilation, changes in Peak systolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  10. Changes in Peak systolic velocity (Short-term memory test)

    Time frame: 30 minutes

    With short-term memory test, changes in Peak systolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  11. Changes in Peak systolic velocity (Vocabulary problems)

    Time frame: 30 minutes

    With solving vocabulary problems, changes in Peak systolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  12. Changes in Peak systolic velocity (Math problems)

    Time frame: 30 minutes

    With solving math problems, changes in Peak systolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  13. Changes in Vend-diastolic velocity (Basal)

    Time frame: 30 minutes

    Changes in Mean Velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  14. Changes in Vend-diastolic velocity (Hypoventilation)

    Time frame: 30 minutes

    By performing Hypoventilation, changes in Vend-diastolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  15. Changes in Vend-diastolic velocity (Hyperventilation)

    Time frame: 30 minutes

    By performing Hyperventilation, changes in Vend-diastolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  16. Changes in Vend-diastolic velocity (Short-term memory test)

    Time frame: 30 minutes

    With short-term memory test, changes in Vend-diastolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  17. Changes in Vend-diastolic velocity (Vocabulary problems)

    Time frame: 30 minutes

    With solving vocabulary problems, changes in Vend-diastolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

  18. Changes in Vend-diastolic velocity (Math problems)

    Time frame: 30 minutes

    With solving math problems, changes in Vend-diastolic velocity, measure in m/s from baseline to 30 minutes after caffeine ingestion.

Secondary outcomes

  1. Changes in Heart Rate (Basal)

    Time frame: 30 minutes

    Changes in Heart Rate, measure in bpm from baseline to 30 minutes after caffeine ingestion.

  2. Changes in Heart Rate (Hypoventilation)

    Time frame: 30 minutes

    By performing Hypoventilation, changes in Heart Rate, measure in bpm from baseline to 30 minutes after caffeine ingestion.

  3. Changes in Heart Rate (Hyperventilation)

    Time frame: 30 minutes

    By performing Hyperventilation, changes in Heart Rate, measure in bpm from baseline to 30 minutes after caffeine ingestion.

  4. Changes in Heart Rate (Short-term memory test)

    Time frame: 30 minutes

    With short-term memory test, changes in Heart Rate, measure in bpm from baseline to 30 minutes after caffeine ingestion.

  5. Changes in Heart Rate (Vocabulary problems)

    Time frame: 30 minutes

    With solving vocabulary problems, changes in Heart Rate, measure in bpm from baseline to 30 minutes after caffeine ingestion.

  6. Changes in Heart Rate (Math problems)

    Time frame: 30 minutes

    With solving math problems, changes in Heart Rate, measure in bpm from baseline to 30 minutes after caffeine ingestion.

Sponsors and collaborators

Lead sponsor

Escola Superior de Tecnologia da Saúde de Coimbra

Other

Registry information

Official study title

Effects of Caffeine on Cerebral Blood Flow in Clinically Healthy Young People

Important dates

Study start
2021
Primary completion
2021
Study completion
2021
First posted
May 19, 2023
Registry last updated
May 19, 2023

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.