Mechanisms Underlying Carbon Dioxide Induced Protein Efflux in Health and Traumatic Brain Injury
Andrew Mayer
Summary
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.
Description
Impaired clearance of metabolic waste and cellular debris is a hallmark of TBI and other neurodegenerative conditions. Clearance primarily occurs through glymphatic/lymphatic pathways, which is partially dependent on the influx of cerebrospinal fluid (CSF). CSF flow is greatest during sleep, when low-frequency oscillations in cerebral blood volume are most prominent. The investigators propose that changing levels of cerebral blood volume via the administration of CO2 will drive CSF flow and ultimately promote brain waste clearance. The proposed study is significant because it examines whether…
Eligibility
- Age range
- 18–82 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion criteria for TBI cohort: 1) Able to give valid informed consent, 2) 18-82 years old, 3) history of TBI of any severity level (mild, moderate or severe) that was sustained in adulthood (age 18 and older), which will be confirmed using a semi-structured identification method (includes asking about loss of consciousness, posttraumatic amnesia, and feeling dazed/confused). Inclusion criteria for Healthy Subjects cohort: 1) Able to give valid informed consent and 2) 18-82 years old years old. Exclusion criteria for TBI cohort: 1) contraindications to MRI scanning including pregnancy or…
Interventions
- OtherHypercapnia task performed during fMRI
This 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.
Location
- The Mind Research NetworkAlbuquerque, New Mexico