Carbon Dioxide Administration and Brain Waste Clearance
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-82
SponsorAndrew Mayer
About this trial
The current study tests whether different exposures to carbon dioxide (CO2) can safely result in the increased movement of proteins from the brain into the blood. The investigators believe that this would be a proxy for the brain clearing waste products more effectively. The current study will use a counter-balanced design, in which individuals with and without a history of traumatic brain injury (TBI) will receive different levels of CO2 (targeted changes of approximately 5 or 10 mmHG in end-tidal CO2) approximately one week apart. The counter-balanced design means that each participant receives a single dose of CO2 at each visit, and different doses of CO2 at each visit. The order in which participants receive the dose is randomized, and the participant will not be informed of the dose.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
None
Disqualifiers
None
Trial design
Design model
Crossover
Treatments tested in this trial
Hypercapnia task performed during fMRI
Other interventionThis study looks at different levels of carbon dioxide (CO2) exposure (changes of approximately 5 or 10 mmHg) on the brain and proteins in blood, in response to a hypercapnia task while participants undergo MRI. This sequence will dynamically mix gases to target an increase of 5 or 10 mmHg in ETCO2 (increase of \~5-7% CO2 and equal decrease in nitrogen) while keeping O2 constant.
Treatment groups
200 Participants
are divided into 2 treatment groupsGroup A: Individuals with TBIExperimental treatment 1 intervention
Group B: Healthy SubjectsExperimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Cerebrovascular Reactivity (CVR), vascular-elicited bulk cerebral spinal fluid (VE-bCSF)
Cerebrovascular reactivity (CVR) will be quantified using time-shifted end-tidal carbon dioxide (ETCO₂) regressors to model blood oxygen level-dependent (BOLD) changes using functional magnetic resonance imaging, capturing the temporally lagged positive relationship between ETCO₂ and the BOLD signal. Vascular enhanced changes in bulk CSF flow will be assessed by regressing band-pass filtered global grey matter signals and their derivatives on CSF bulk flow to capture the temporally lagged, negative relationship. Both of these measurements are in arbitrary units, and will be quantified by calculating percent signal change and statistical fit between regressors.
Time frame
2.5 hours post-intervention. Data will be reported at the conclusion of the study for all participants.2
Protein Efflux (Surrogate Measure of Brain Waste Clearance)
Protein efflux from the brain to the blood will be measured using Quanterix platform, with primary proteins including neurofilament light chain, brain-derived tau and glial fibrillary acidic protein (units=picogram/milligram). For neurofilament light chain (NfL), the limit of detection (LOD) is 0.104 pg/mL, the range is 0.025-0.276 pg/mL, and the lower limit of quantification (LLOQ) is 0.241 pg/mL. For glial fibrillary acidic protein (GFAP), the LOD is 0.221 pg/mL, the range is 0.042-0.481 pg/mL, and the LLOQ is 0.467 pg/mL. For brain-derived tau (BD Tau), the LOD is 0.024 pg/mL, the range is 0.007-0.059 pg/mL, and the LLOQ is 0.053 pg/mL. All values are obtained from the Quanterix website datasheets.
Time frame
Blood will be drawn at baseline, immediately prior to hypercapnia, 45 minutes post-hypercapnia, 90 minutes post-hypercapnia and 150 minutes post-hypercapnia. Data will be reported at the conclusion of the study for all participants.Secondary outcomes
1
Symptoms
Participants will be asked to rate 4 different symptoms (current headache, current dizziness, current nausea, and current fogginess) on a Likert scale (range 0-10 for each symptom) at multiple times during the study. Symptom ratings will be summed to create a single summary score that can range between 0 and 40.
Time frame
After the first blood draw (i.e., blood collected at baseline), 10 and 20 minutes post-hypercapnia, as well as after blood collected 90-minutes post-hypercapnia. Data will be reported at the conclusion of the study for all participants.Sponsors and contacts
Click on the lead sponsor to view all of their trials.
Andrew Mayer
Lead sponsor
The Mind Research Network
Sponsor institution
Source ClinicalTrials.gov