Brain Blood Vessel Responses to Changes in Blood Flow

Cerebrovascular Responses to Acute Hypoperfusion

Brain blood flow will be measured during a simulated postural change test and while breathing increased levels of carbon dioxide using magnetic resonance imaging.

Study Overview

• Status: Recruiting
• Conditions: Magnetic Resonance Imaging; Cerebrovascular Circulation
• Intervention / Treatment: Drug: Placebo; Device: MRI; Drug: Prazosin

Detailed Description

Global cerebral blood flow (CBF) decreases with advancing age; however, some adults have accelerated declines in CBF, placing them at a greater risk of cognitive impairment. However, there is a lack of human studies that investigate the cause or consequence of altered blood flow regulation in the brain. This study will systematically address this gap in knowledge by examining cerebrovascular control in adults during acute physiological challenges (simulated postural change test and breathing increased carbon dioxide) that stimulate a change in CBF.

• Study Type: Interventional
• Enrollment (Estimated): 36
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Anna Howery; Phone Number: 608-262-9572; Email: ahowery@wisc.edu

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53705
      • Recruiting
      • University of Wisconsin
      • Contact: Anna J Howery, MS; Phone Number: 608-262-9572; Email: barneslab@education.wisc.edu
      • Principal Investigator: Jill N Barnes, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

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).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Middle-Aged Adults; Middle-Aged Adults between 55-69 years of age.	Drug: Placebo; Oral placebo; Device: MRI; Participants will undergo an MRI scan while performing breathing and a simulated postural change task.; Drug: Prazosin; A dose of prazosin will be administered based on body weight.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in blood flow	The change in intracranial blood flow during breathing and simulated postural change tasks will be measured with MRI	Two study visits, up to 240 minutes
Change in blood velocity	The change in blood velocity during breathing and simulated postural change tasks will be measured with MRI.	Two study visits, up to 240 minutes

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison
• Collaborators: National Institute of Neurological Disorders and Stroke (NINDS)
• Investigators: Principal Investigator: Jill Barnes, PhD, UW Madison

Study record dates

Study Major Dates

• Study Start (Actual): February 26, 2026
• Primary Completion (Estimated): January 1, 2027
• Study Completion (Estimated): January 1, 2027

Study Registration Dates

• First Submitted: October 4, 2024
• First Submitted That Met QC Criteria: October 4, 2024
• First Posted (Actual): October 8, 2024

Study Record Updates

• Last Update Posted (Actual): March 2, 2026
• Last Update Submitted That Met QC Criteria: February 27, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Magnetic Resonance Imaging; Brain Blood Flow; Carbon Dioxide; Lower Body Negative Pressure
• Additional Relevant MeSH Terms: Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Quinazolines; Prazosin
• Other Study ID Numbers: 2024-0377; A176000 (Other Identifier: UW Madison); EDUC/KINESIOLOGY (Other Identifier: UW Madison); 1RF1NS117746-01 (U.S. NIH Grant/Contract); Protocol Version7/29/2025 (Other Identifier: UW- Madison)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No