How brain blood vessels respond to changes in blood flow
Cerebrovascular Responses to Acute Hypoperfusion
This project will test how brain blood flow changes during a simulated postural change and when breathing higher levels of carbon dioxide in adults aged 55–69.
Quick facts
| Phase | Phase 2 |
|---|---|
| Study type | Interventional |
| Enrollment | 36 (estimated) |
| Ages | 55 Years to 69 Years |
| Sex | All |
| Sponsor | University of Wisconsin, Madison Academic / other |
| Locations | 1 site (Madison, Wisconsin) |
| Trial ID | NCT06629077 on ClinicalTrials.gov |
What this trial studies
This Phase 2 interventional protocol uses MRI to measure global and regional cerebral blood flow while participants undergo two controlled physiological challenges: a simulated postural change using lower body negative pressure and brief inhalation of elevated carbon dioxide. Participants who meet inclusion criteria will receive either the alpha-1 blocker prazosin or placebo to probe the role of sympathetic signaling in cerebrovascular control. MRI scans will be performed before, during, and after each challenge to quantify cerebrovascular reactivity and compare responses by drug condition. The study aims to identify alterations in blood flow regulation that could explain accelerated declines in cerebral perfusion with age.
Who should consider this trial
Good fit: Ideal candidates are nonsmoking adults aged 55–69, BMI ≤34.5 kg/m2, shorter than 72 inches, with postmenopausal females and no major cardiovascular, cerebrovascular, hepatic, renal, hematologic, uncontrolled hypertensive, diabetic, neurologic, or recent major psychiatric conditions.
Not a fit: People with diagnosed mild cognitive impairment or Alzheimer’s, significant cardiovascular or cerebrovascular disease, uncontrolled hypertension, severe untreated sleep apnea, recent major psychiatric disorders, or diabetes with very high HbA1c are unlikely to benefit or qualify for participation.
Why it matters
Potential benefit: If successful, this work could help identify people with impaired cerebrovascular regulation and point toward therapies to protect brain blood flow and reduce risk of cognitive decline.
How similar studies have performed: Previous human studies have used carbon dioxide inhalation and orthostatic challenges to measure cerebrovascular reactivity, but combining these MRI measures with pharmacologic alpha-1 blockade in this way is relatively novel.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria: * Between the ages of 55-69 years * Have a BMI less than or equal to 34.5 kg/m2 * Nonsmoker * are less than 72 in (182.88 cm) height * Females must be postmenopausal Exclusion Criteria: * Diagnosis of Mild Cognitive Impairment (MCI) or Alzheimer's disease (AD) * History or evidence of hepatic disease, hematological disease, or peripheral vascular disease; severe kidney injury requiring hemodialysis * History of cardiovascular disease including: severe congestive heart failure, coronary artery disease, ischemic heart disease (stents, coronary artery bypass grafts) and tachycardia * Uncontrolled hypertension * History of clinically significant ischemic or hemorrhagic stroke, or significant cerebrovascular disease * Severe untreated obstructive sleep apnea * History of diabetes with HbA1c greater than 9.5% * Major neurologic disorders other than dementia (e.g., MS, ALS, brain surgery, etc.) * Current or recent (\<1 year) major psychiatric condition (Axis I) or addictive disorders * Significant surgical history * Other significant medical conditions at investigators' discretion * Contraindications to MRI * Prescribed medications that interfere with prazosin * Lactose allergy * lower body will not fit in lower body negative pressure (LBNP) chamber (regardless of overall height and BMI).
Where this trial is running
Madison, Wisconsin
- University of Wisconsin — Madison, Wisconsin, United States (Recruiting)
Study contacts
- Principal investigator: Jill Barnes, PhD — UW Madison
- Study coordinator: Anna Howery
- Email: ahowery@wisc.edu
- Phone: 608-262-9572
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.