Healthy Brain PerfusionNCT05164705
Improving Human Cerebrovascular Function Using Acute Intermittent Hypoxia
A study testing Acute Intermittent Hypoxia in people with Healthy Brain Perfusion, run by Northwestern University at 1 site in United States.
Trial summary
This study uses magnetic resonance imaging to determine whether 3 weeks of repeated exposure to Acute Intermittent Hypoxia can improve brain blood flow or blood flow regulation in healthy adults. Read more about this study
- Who is it for?
- Ages 21 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Brain Perfusion
- What is being tested?
- Acute Intermittent Hypoxia
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 33 participants
- Where
- 1 siteUnited States
- Study dates
- 3 May 2022to 5 Apr 2024
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 21 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy volunteers between ages of 21 and 50 years
- No known neurological, respiratory or vascular conditions
- Safe to be scanned using MRI
- Able to communicate in English
Who cannot join
- MRI contraindications as indicated on MRI safety screening form
- Subjects with pacemakers, cochlear (in the ear) implants, or aneurysm clips or subjects who have worked with metal
- Pregnant women
- Individuals with known neurological or vascular conditions
- Individuals with sleep apnea, emphysema, or other respiratory conditions
- Individuals with severe claustrophobia
Show all 15Show fewer
- Subjects unwilling or unable to give written informed consent in English
- Prisoners
- Frequent smoker
- Allergy to Tegaderm
- Blood pressure greater than 140/90 or less than 90/55.
- Individuals who report headaches, feeling dizzy or light-headed, or have heart palpitations on the day of the study.
- Individuals prescribed Aripiprazole and/or Lamotrigine*
- Note, mild (well-controlled) asthma is not immediate grounds for exclusion.
- Other prescription medications may be grounds for exclusion; prescription medication information will be acquired during initial screening and at subsequent follow-up visits
Trial locations and contacts
1 site in 1 country.
About this study
This study uses magnetic resonance imaging to determine whether 3 weeks of repeated exposure to Acute Intermittent Hypoxia can improve brain blood flow or blood flow regulation in healthy adults.
Read the detailed description
This study aims to identify an intervention to improve the function of blood vessels in the human brain, in order to mitigate damage to overall brain function and improve health outcomes across the lifespan. Hypoxia is a potent driver of angiogenesis and vascular plasticity, and acute intermittent hypoxia (AIH) protocols, in which an individual alternates between breathing mildly hypoxic air and normal air, are being rigorously examined for their potential in improving human physiology. This study tests whether AIH evokes beneficial vascular plasticity in the human brain, using a randomized crossover design to determine the impact of different daily AIH or sham interventions on MRI measures of cerebrovascular physiology.
Healthy, able-bodied participants between 21 and 50 years old will be invited to participate in this study. The daily AIH intervention consists of repeated visits to the PI laboratory over a three-week period to have an AIH or sham protocol administered via a hypoxia generator and face mask (Hyp-123, Hypoxico). Blood pressure readings will be taken before and after all intervention visits, and SpO2 levels continuously recorded for safety monitoring.
The effectiveness of the different interventions at improving cerebrovascular function will be assessed using MRI. In the week prior to each intervention period the participant will undergo MRI scanning. In addition to structural and diffusion weighted scans, multiple perfusion metrics will be extracted. Whole-brain cerebral blood flow will be measured using phase-contrast MRI, and quantitative CBF maps of regional perfusion will be measured using arterial spin labeling MRI. These perfusion metrics will be acquired three times: during normoxic (baseline), hypoxic, and hypercapnic conditions. Changes in perfusion values during gas challenges will measure whole-brain and regional cerebrovascular reactivity. The MRI protocol will be repeated one day after the last intervention visit.
- Conditions
- Healthy Brain Perfusion
- Being tested
- Acute Intermittent Hypoxia, Sham Acute Intermittent Hypoxia
- Keywords
- Acute Intermittent Hypoxia, MRI, Perfusion, Cerebral Blood Flow, Cerebrovascular Reactivity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Acute Intermittent HypoxiaOther
Participants will wear a non-rebreathing face mask and alternate between breathing 9% O2 gas mixture for up to 1 minute, or until the target SpO2 of 85 percent is reached, and normal room air (21 percent O2) until 2 minutes are complete. This cycle will be repeated 15 times, resulting in a 30-minute protocol.
Sham Acute Intermittent HypoxiaOther
Participants will wear a non-rebreathing face mask and breathe normal air (21 percent O2) for 30-minutes.
| Study group | Role | What they receive |
|---|---|---|
| Intermittent Hypoxia | Active comparator | Participant will visit our center 2-4 times per week for three weeks to receive Acute Intermittent Hypoxia. Receives: Other: Acute Intermittent Hypoxia |
| Sham Intermittent Hypoxia | Sham comparator | Participants will visit our center 2-4 times per week for three weeks to receive Sham Intermittent Hypoxia. Receives: Other: Sham Acute Intermittent Hypoxia |
What is being measured
The primary outcome is the main question the study is designed to answer.
Resting Cerebral Blood Flow
Phase-contrast MRI and Arterial Spin Labeling MRI will be used to quantify whole-brain and cortical gray matter perfusion (ml/100g/min) before and after the 3-week intervention.
Measured: 4 weeks
Secondary outcomes (1)
Cerebrovascular Reactivity
Phase-contrast MRI and Arterial Spin Labeling MRI will be used to quantify the change in perfusion caused by a vasodilatory gas challenge (inhaled hypoxia or hypercapnia), before and after the 3-week intervention.
Measured: 4 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Dec 2021
- Study start3 May 2022
- Primary completion5 Apr 2024
- Study completion5 Apr 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Healthy Brain PerfusionStudies of the same condition, open and under way.
- More trials run by Northwestern UniversityThe sponsor's other registered studies.
- 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
- Model description
- Randomized sham-controlled crossover trial
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 33 participants (actual)
Sponsor and investigators
- Lead sponsor
- Northwestern University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Molly G Bright, DPhil, Principal investigator, Northwestern University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05164705
- Sponsor's protocol ID
- STU00215559
- Status last verified
- Jun 2026
- First submitted
- 7 Dec 2021
- Last updated
- 20 Jul 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: MR imaging data and the associated physiologic data collected during MRI scanning will be shared in an anonymized format, along with the extracted quantitative perfusion maps and cerebrovascular reactivity maps. These data will be made available to public through the Open Science Framework (osf.io) or similar public repository. Code will be made available through the PI's laboratory Github account. A link to these resources will be included with publications resulting from this study to facilitate access.
Publications
Johnson HR, Wang MC, Stickland RC, Chen Y, Parrish TB, Sorond FA, Bright MG. Variable cerebral blood flow responsiveness to acute hypoxic hypoxia. Front Physiol. 2025 Mar 12;16:1562582. doi: 10.3389/fphys.2025.1562582. eCollection 2025.
PubMed 40144550
Study at a glance
From the registry record, last updated by the sponsor on 20 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Improving Human Cerebrovascular Function Using Acute Intermittent Hypoxia
- ClinicalTrials.gov ID
- NCT05164705
- Acronym / sponsor ID
- STU00215559
- Conditions
- Healthy Brain Perfusion
- Keywords
- Acute Intermittent Hypoxia, MRI, Perfusion, Cerebral Blood Flow, Cerebrovascular Reactivity
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 33 participants (actual)
- Lead sponsor
- Northwestern UniversityUniversity, hospital or other
- Study start
- 3 May 2022 (actual)
- Primary completion
- 5 Apr 2024 (actual)
- Study completion
- 5 Apr 2024 (actual)
- First posted
- 21 Dec 2021 (actual)
- Results
- Posted 20 Jul 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study uses magnetic resonance imaging to determine whether 3 weeks of repeated exposure to Acute Intermittent Hypoxia can improve brain blood flow or blood flow regulation in healthy adults.
Detailed description
This study aims to identify an intervention to improve the function of blood vessels in the human brain, in order to mitigate damage to overall brain function and improve health outcomes across the lifespan. Hypoxia is a potent driver of angiogenesis and vascular plasticity, and acute intermittent hypoxia (AIH) protocols, in which an individual alternates between breathing mildly hypoxic air and normal air, are being rigorously examined for their potential in improving human physiology. This study tests whether AIH evokes beneficial vascular plasticity in the human brain, using a randomized crossover design to determine the impact of different daily AIH or sham interventions on MRI measures of cerebrovascular physiology.
Healthy, able-bodied participants between 21 and 50 years old will be invited to participate in this study. The daily AIH intervention consists of repeated visits to the PI laboratory over a three-week period to have an AIH or sham protocol administered via a hypoxia generator and face mask (Hyp-123, Hypoxico). Blood pressure readings will be taken before and after all intervention visits, and SpO2 levels continuously recorded for safety monitoring.
The effectiveness of the different interventions at improving cerebrovascular function will be assessed using MRI. In the week prior to each intervention period the participant will undergo MRI scanning. In addition to structural and diffusion weighted scans, multiple perfusion metrics will be extracted. Whole-brain cerebral blood flow will be measured using phase-contrast MRI, and quantitative CBF maps of regional perfusion will be measured using arterial spin labeling MRI. These perfusion metrics will be acquired three times: during normoxic (baseline), hypoxic, and hypercapnic conditions. Changes in perfusion values during gas challenges will measure whole-brain and regional cerebrovascular reactivity. The MRI protocol will be repeated one day after the last intervention visit.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- Randomized sham-controlled crossover trial
| Arm | Type | Receives |
|---|---|---|
| Intermittent Hypoxia | Active comparator | Other: Acute Intermittent HypoxiaParticipant will visit our center 2-4 times per week for three weeks to receive Acute Intermittent Hypoxia. |
| Sham Intermittent Hypoxia | Sham comparator | Other: Sham Acute Intermittent HypoxiaParticipants will visit our center 2-4 times per week for three weeks to receive Sham Intermittent Hypoxia. |
Who may qualify
- Ages
- 21 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Healthy volunteers between ages of 21 and 50 years
- No known neurological, respiratory or vascular conditions
- Safe to be scanned using MRI
- Able to communicate in English
Key exclusion criteria (15 listed)
- MRI contraindications as indicated on MRI safety screening form
- Subjects with pacemakers, cochlear (in the ear) implants, or aneurysm clips or subjects who have worked with metal
- Pregnant women
- Individuals with known neurological or vascular conditions
- Individuals with sleep apnea, emphysema, or other respiratory conditions
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 |
|---|---|---|
| Acute Intermittent HypoxiaParticipants will wear a non-rebreathing face mask and alternate between breathing 9% O2 gas mixture for up to 1 minute, or until the target SpO2 of 85 percent is reached, and normal room air (21 percent O2) until 2 minutes are complete. This cycle will be repeated 15 times, resulting in a 30-minute protocol. | Other | Intermittent Hypoxia |
| Sham Acute Intermittent HypoxiaParticipants will wear a non-rebreathing face mask and breathe normal air (21 percent O2) for 30-minutes. | Other | Sham Intermittent Hypoxia |
Primary outcome
Resting Cerebral Blood Flow
Time frame: 4 weeks
Phase-contrast MRI and Arterial Spin Labeling MRI will be used to quantify whole-brain and cortical gray matter perfusion (ml/100g/min) before and after the 3-week intervention.
1 secondary outcome
Cerebrovascular Reactivity
Time frame: 4 weeks
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 Jul 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 40144550Johnson HR, Wang MC, Stickland RC, Chen Y, Parrish TB, Sorond FA, Bright MG. Variable cerebral blood flow responsiveness to acute hypoxic hypoxia. Front Physiol. 2025 Mar 12;16:1562582. doi: 10.3389/fphys.2025.1562582. eCollection 2025.
- Individual participant dataSharing planned: Yes. MR imaging data and the associated physiologic data collected during MRI scanning will be shared in an anonymized format, along with the extracted quantitative perfusion maps and cerebrovascular reactivity maps. These data will be made available to public through the Open Science Framework (osf.io) or similar public repository. Code will be made available through the PI's laboratory Github account. A link to these resources will be included with publications resulting from this study to facilitate access.
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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.
Molly G Bright, DPhil principal investigator
Northwestern University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Acute Intermittent Hypoxia in people with Healthy Brain Perfusion, run by Northwestern University at 1 site in United States.
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 4 inclusion and 15 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: finished, as of the sponsor's last update on 20 Jul 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 United States. 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?
Yes. Results are posted in the registry (first posted 20 Jul 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Resting Cerebral Blood Flow (time frame: 4 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05164705, which also lists 1 linked publication.
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 20 Jul 2026.