HealthyNCT05292378
Carbon Dioxide (CO2) and Cognitive Impairment
A study testing 2500 ppm Carbon Dioxide and 600 ppm Carbon Dioxide in people with Healthy, run by Rutgers, The State University of New Jersey at 1 site in United States.
Trial summary
The purpose of the study is to better understand the biological mechanisms of carbon dioxide (CO2)-induced cognitive impairments. Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy
- What is being tested?
- 2500 ppm Carbon Dioxide and 600 ppm Carbon Dioxide
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 27 participants
- Where
- 1 siteUnited States
- Study dates
- 14 Jul 2022to 20 Mar 2025
- 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 18 to 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- History of COVID-19 vaccination
- Weigh at least 110 pounds
Who cannot join
- Colorblindness
- Inability to hear verbal instructions
- Cardiovascular disease, including a history of stroke
- Diabetes requiring the use of insulin
- Pregnancy
- Current asthma (an asthma attack within the past five years)
Show all 23Show fewer
- Medications for or history of anxiety disorder diagnosis or panic attacks
- Medications which may affect cognition such as beta-blockers and CNS depressants
- Temporary Exclusion Criteria
- Respiratory symptoms in the previous four weeks
- Use of sedating cold/allergy medications in the previous week
- Use of marijuana in the previous week
- Consumption of alcohol in the previous 24 hours
- Additional Exclusion Criteria for Subjects undergoing the fMRI scan:
- History of head trauma or neurosurgery or neurological disorder
- Ferrous metal implanted in or on the body, electrical devices such as a pacemaker, nonremovable ferrous jewelry
- Surgical pins or plates above the neck
- History of eye injury involving metallic materials, shavings in eyes, or welding without a face mask
- Lead or iron tatoos
- Claustrophobia
- Back problems that would prevent the subject from laying still comfortably for up to 90 minutes
- Additional Exclusion Criteria for Subjects undergoing CAIM
- Current or recent contact lens use
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Carbon Dioxide (CO2): A Pilot Study of a Hypothesized Mechanism to Explain Cognitive Impairment
The purpose of the study is to better understand the biological mechanisms of carbon dioxide (CO2)-induced cognitive impairments.
Read the detailed description
Participants will complete 2 study visits. Each study visit will consist of a 2.5-hour exposure session. Concentrations of CO2 during the exposure session will be either 600 ppm (control) or 2500 ppm (exposure). The order of the exposure sessions will be randomized and the exposure sessions will be at least one week apart. Up to two participants will take part in each exposure session.
During each exposure a neurobehavioral assessment (Strategic Management Simulations or SMS) will be administered. Venous blood (30 mL) will be collected from subjects immediately before entering the chamber and immediately after the exposure. A subset of subjects (n=12) will also undergo a 60-minute fMRI scan. Another subset of subjects (up to 10) will not complete the SMS during the exposures but will undergo computer-assisted intravital microscopy (CAIM) to exam the conjunctival microvasculature before and after the exposure.
- Conditions
- Healthy
- Being tested
- 2500 ppm Carbon Dioxide, 600 ppm Carbon Dioxide
- Keywords
- Carbon Dioxide, Cognitive Impairment
- Medical subject headings
- Cognitive Dysfunction
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
2500 ppm Carbon DioxideOther
2.5 hour exposure to 2500 ppm carbon dioxide
600 ppm Carbon DioxideOther
2.5 hour exposure to 600 ppm carbon dioxide
| Study group | Role | What they receive |
|---|---|---|
| High CO2 Exposure first, then low CO2 exposure second. | Experimental | At the first study visit the subject is exposed to 2500 ppm CO2 for 2.5 hours and at the second study visit the subject is exposed to 600 ppm CO2 for 2.5 hours. Receives: Other: 2500 ppm Carbon Dioxide; Other: 600 ppm Carbon Dioxide |
| Low CO2 Exposure first, then high CO2 exposure second. | Sham comparator | At the first study visit the subject is exposed to 600 ppm CO2 for 2.5 hours and at the second study visit the subject is exposed to 2500 ppm CO2 for 2.5 hours. Receives: Other: 2500 ppm Carbon Dioxide; Other: 600 ppm Carbon Dioxide |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Basal Oxygen Consumption (OCR)
Using blood samples collected 4 hours post-exposure, PMN activation was assessed by measurement of oxidative burst (oxygen consumption rate).
Measured: 4 hours after each exposure
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Total Stimulated Oxygen Consumption.
Using blood samples collected 4 hours post-exposure, PMN activation was assessed by measurement of total stimulated oxygen consumption.
Measured: 4 hours after each exposure
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Time to Peak (TTP) Oxygen Consumption
Using blood samples collected 4 hours post-exposure, PMN activation was assessed by measurement of time to peak (TTP) oxygen consumption.
Measured: 4 hours after each exposure
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Mar 2022
- Study start14 Jul 2022
- Primary completion20 Mar 2025
- Study completion20 Mar 2025
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.
- Other trials for HealthyStudies of the same condition, open and under way.
- More trials run by Rutgers, The State University of New JerseyThe 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
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 27 participants (actual)
Sponsor and investigators
- Lead sponsor
- Rutgers, The State University of New Jersey
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Howard M. Kipen, MD, MPH, Rutgers, The State University of New Jersey
- Investigators
- Howard Kipen, MD, Principal investigator, Professor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05292378
- Sponsor's protocol ID
- Pro2021001570
- Status last verified
- Feb 2026
- First submitted
- 24 Jan 2022
- Last updated
- 16 Mar 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: There is no plan to make individual participant data available to other researchers.
Study at a glance
From the registry record, last updated by the sponsor on 16 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Carbon Dioxide (CO2): A Pilot Study of a Hypothesized Mechanism to Explain Cognitive Impairment
- ClinicalTrials.gov ID
- NCT05292378
- Acronym / sponsor ID
- Pro2021001570
- Conditions
- Healthy
- Keywords
- Carbon Dioxide, Cognitive Impairment
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 27 participants (actual)
- Lead sponsor
- Rutgers, The State University of New JerseyUniversity, hospital or other
- Study start
- 14 Jul 2022 (actual)
- Primary completion
- 20 Mar 2025 (actual)
- Study completion
- 20 Mar 2025 (actual)
- First posted
- 23 Mar 2022 (actual)
- Results
- Posted 16 Mar 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of the study is to better understand the biological mechanisms of carbon dioxide (CO2)-induced cognitive impairments.
Detailed description
Participants will complete 2 study visits. Each study visit will consist of a 2.5-hour exposure session. Concentrations of CO2 during the exposure session will be either 600 ppm (control) or 2500 ppm (exposure). The order of the exposure sessions will be randomized and the exposure sessions will be at least one week apart. Up to two participants will take part in each exposure session.
During each exposure a neurobehavioral assessment (Strategic Management Simulations or SMS) will be administered. Venous blood (30 mL) will be collected from subjects immediately before entering the chamber and immediately after the exposure. A subset of subjects (n=12) will also undergo a 60-minute fMRI scan. Another subset of subjects (up to 10) will not complete the SMS during the exposures but will undergo computer-assisted intravital microscopy (CAIM) to exam the conjunctival microvasculature before and after the exposure.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| High CO2 Exposure first, then low CO2 exposure second. | Experimental | Other: 2500 ppm Carbon Dioxide, Other: 600 ppm Carbon DioxideAt the first study visit the subject is exposed to 2500 ppm CO2 for 2.5 hours and at the second study visit the subject is exposed to 600 ppm CO2 for 2.5 hours. |
| Low CO2 Exposure first, then high CO2 exposure second. | Sham comparator | Other: 2500 ppm Carbon Dioxide, Other: 600 ppm Carbon DioxideAt the first study visit the subject is exposed to 600 ppm CO2 for 2.5 hours and at the second study visit the subject is exposed to 2500 ppm CO2 for 2.5 hours. |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- History of COVID-19 vaccination
- Weigh at least 110 pounds
Key exclusion criteria (23 listed)
- Colorblindness
- Inability to hear verbal instructions
- Cardiovascular disease, including a history of stroke
- Diabetes requiring the use of insulin
- Pregnancy
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 |
|---|---|---|
| 2500 ppm Carbon Dioxide2.5 hour exposure to 2500 ppm carbon dioxide | Other | High CO2 Exposure first, then low CO2 exposure second., Low CO2 Exposure first, then high CO2 exposure second. |
| 600 ppm Carbon Dioxide2.5 hour exposure to 600 ppm carbon dioxide | Other | High CO2 Exposure first, then low CO2 exposure second., Low CO2 Exposure first, then high CO2 exposure second. |
Primary outcome
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Basal Oxygen Consumption (OCR)
Time frame: 4 hours after each exposure
Using blood samples collected 4 hours post-exposure, PMN activation was assessed by measurement of oxidative burst (oxygen consumption rate).
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Total Stimulated Oxygen Consumption.
Time frame: 4 hours after each exposure
Using blood samples collected 4 hours post-exposure, PMN activation was assessed by measurement of total stimulated oxygen consumption.
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Time to Peak (TTP) Oxygen Consumption
Time frame: 4 hours after each exposure
Using blood samples collected 4 hours post-exposure, PMN activation was assessed by measurement of time to peak (TTP) oxygen consumption.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Mar 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No. There is no plan to make individual participant data available to other researchers.
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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.
Howard Kipen, MD principal investigator
Professor
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing 2500 ppm Carbon Dioxide and 600 ppm Carbon Dioxide in people with Healthy, run by Rutgers, The State University of New Jersey 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 2 inclusion and 23 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 16 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 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 16 Mar 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?
Change in PMN (Polymorphonuclear Leukocyte) Activation as Measured by Basal Oxygen Consumption (OCR) (time frame: 4 hours after each exposure). The study lists 3 primary outcomes in all. 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 16 Mar 2026.