Exploring Sympathetic Nervous System Function in Individuals With Down Syndrome

This study is looking at how the 'fight-or-flight' response, controlled by your sympathetic nervous system (SNS), works in people with Down syndrome. The SNS helps your body react to stress by increasing heart rate and blood pressure. Researchers will measure levels of certain chemicals called catecholamines (like adrenaline) in your blood after different triggers, such as fear, cold, pain, caffeine, and a 12-hour fast. This will help them understand how the SNS functions in individuals with Down syndrome, who often have differences in how their heart rate responds to activity. The study is currently unclear on its recruitment status and plans to enroll 200 participants aged 18 to 50 years old who can understand the study and have a study partner.

Study design: This is an interventional study, meaning participants will receive specific triggers. It plans to enroll 200 individuals.
What's involved: You would undergo tests involving fear, cold, pain, caffeine, and a 12-hour fast. Blood samples will be taken at baseline and during these tests.
Compensation: Not stated in the trial record.
Follow-up: Blood samples will be taken at seated baseline, during the cold stress test (up to 5 minutes), and at standing baseline.

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Exploring Sympathetic Nervous System Function in Individuals With Down Syndrome

Recruiting

PHASE3Ages 18–50InterventionalPrevention

University of Colorado, Denver

~200 participants

Updated 2026-05-04 on ClinicalTrials.gov

What's tested:Fear ResponseCold StressPain ResponseCaffeine12-Hour FastMaximal Dynamic Exercise

At a glance

Recruiting sites

1 of 1 listed site is recruiting right now

RecruitingSuspended, closed, or not yet open

What they're measuring

Seated Baseline Concentration of Plasma Catecholamines

Measured over Seated baseline blood draw, prior to stressors

+42 more outcomes measured

Conditions

Down Syndrome

Autonomic Dysfunction

Where it's being run

1 sites across 1 states

Colorado1

Who to contact

Sara R Sherman, PhD

[email protected]

303-724-0598

Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

18-50 yrs old and apparently healthy individuals

Ability to understand the study and give assent to participate

Has a study partner who can attend all visits for the individuals with DS, and answer questionnaires, provide consent when necessary

Corrected or non-existent congenital heart disease

Euthyroid or on stable thyroid medication dose for at least 6 months

Free from cardiovascular, pulmonary, inflammatory, or metabolic disease in the past 6 months that would prevent participation in study procedures

BMI \<45kg/m2

Ability to tolerate repeated blood draws / catheter placement

Exclusion

Hypertension (resting systolic blood pressure \[SBP\] ≥140 and/or diastolic blood pressure \[DBP\] ≥90 mmHg) this includes those on medications to treat hypertension

Hypotension (resting BP of \<90/60 mmHg)

Cancer in the last six months

Any heart-rate-altering medications or any other medication that may modify metabolic responses

Self-reported diabetes or use of glucose-lowering medication

Tobacco products, including vaping, or marijuana use

Currently pregnant

Post-menopausal women

Orthopedic limitations that would prohibit exercise or movement for exercise

Fracture of limb to be immersed for CPT

Open cut or sore on hand to be immersed for CPT

Raynaud's syndrome for CPT

Chronic caffeine drinkers for caffeine stressor (consumption of caffeine in the last 7 days)

What this trial measures

Seated Baseline Concentration of Plasma CatecholaminesSeated baseline blood draw, prior to stressors
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Concentration of Plasma Catecholamines During Cold Pressor TestDuring the cold stress test, around or up to 5 minutes
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Baseline Standing Concentration of Plasma CatecholaminesStanding baseline blood draws, prior to fear simulation
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
First Fear Simulation, Concentration of Plasma CatecholaminesDuring the first virtual reality fear stressor, around 5 minutes
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Second Fear Simulation, Concentration of Plasma CatecholaminesDuring the second fear simulation, around 15 minutes into the test
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
First Minute of Pain Patch, Concentration of Plasma CatecholaminesBlood draw will take place within 1-minute of the application of the pain patch.
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
15 Minutes into Pain Patch Application, Concentration of Plasma CatecholaminesBlood draw will occur about 15 minutes after the application of the pain patch.
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
12-Hour Fast, Concentration of Plasma CatecholaminesBlood draw will occur following a 12-hour fast inducing hypoglycemia
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Seated Baseline Blood Draw, Concentration of Plasma CatecholaminesBlood draw will occur prior to ingestion of caffeine pill
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
30 Minutes Following Ingestion of Caffeine Pill(s), Concentration of Plasma CatecholaminesBlood draw will occur around 30 minutes following participant ingestion of caffeine pill(s)
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
60 Minutes Following Ingestion of Caffeine Pill(s), Concentration of Plasma CatecholaminesBlood draw will occur around 60 minutes following participant ingestion of caffeine pill(s)
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Baseline Standing Concentration of Plasma Catecholamines Prior to Maximal Exercise TestStanding baseline blood draw, prior to maximal exercise test
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Standing Concentration of Plasma Catecholamines at End of Maximal Exercise TestThis blood draw will occur at the very end or immediately following the maximal exercise test on the treadmill
Investigators will use metabolomic techniques to quantify plasma concentrations of epinephrine, norepinephrine, and dopamine in all participants before, during (in some stressors), and after the six stressor tests. These metabolites will provide insight into sympathetic nervous system activation in individuals with Down syndrome compared to those without Down syndrome.
Seated Baseline Heart Rate, Prior to Cold Pressor TestResting seated baseline, prior to cold pressor test, up to or around 5 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during (in some stressors), and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate Collected During Cold Pressor TestCollected throughout the Cold Pressor Test, around 6 minutes in total
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Standing Baseline Heart Rate, Prior to Fear SimulationsStanding baseline, prior to fear simulations, up to or around 5 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, First Fear SimulationContinuous heart rate will be collected during the first fear simulation, which will last around or up to 10 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, First Calming SimulationContinuous heart rate will be recorded during the first calming simulation, which will follow the first fear simulation and will last up to or around 10 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Second Fear SimulationContinuous heart rate will be recorded during the second fear simulation, which will follow the first calming simulation and will last up to or around 10 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Second Calming SimulationContinuous heart rate will be recorded during the second calming simulation, which will follow the second fear simulation and will last up to or around 10 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Baseline Prior to Pain PatchBaseline seated heart rate recordings will occur prior to application of pain patch, up to or around 5 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, During Pain PatchContinuous heart rate will be recorded following the application of the capsaicin pain patch, up to or around 15 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Baseline 12-Hour FastResting baseline will be recorded prior (and on a separate day from) the 12-hour fast, up to or around 5 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, 12-Hour FastSeated heart rate recordings will occur following a 12-hour fast, up to or around 15 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Seated Baseline, Caffeine ConsumptionResting baseline heart rate will be recording prior to caffeine consumption, up to or around 5 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Following Caffeine ConsumptionContinuous heart rate recordings will occur immediately following caffeine consumption, up to or around 60 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Baseline Prior to Maximal Exercise TestBaseline heart rate recordings will occur prior to the maximal exercise test, up to or around 5 minutes.
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Heart Rate, Maximal Exercise TestContinuous heart rate recordings will take place throughout the maximal aerobic exercise test on the treadmill, up to or around 20 minutes
Investigators will collect beat-to-beat heart rate recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Seated Baseline Blood Pressure, Prior to Cold Pressor TestResting seated baseline, prior to cold pressor test, up to or around 5 minutes
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure Collected During Cold Pressor TestCollected throughout the Cold Pressor Test, around 6 minutes in total
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Standing Baseline Blood Pressure, Prior to Fear SimulationsStanding baseline, prior to fear simulations, up to or around 5 minutes
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, First Fear SimulationContinuous blood pressure will be recorded during the first fear simulation, which will last up to or around 10 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, First Calming SimulationContinuous blood pressure will be recorded during the first calming simulation, which will follow the first fear simulation and will last up to or around 10 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Second Fear SimulationContinuous blood pressure will be recorded during the second fear simulation, which will follow the first calming simulation and will last up to or around 10 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Second Calming SimulationContinuous blood pressure will be recorded during the second calming simulation, which will follow the second fear simulation and will last up to or around 10 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Baseline Prior to Pain PatchBaseline seated blood pressure recordings will occur prior to application of pain patch, up to or around 5 minutes
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, During Pain PatchContinuous blood pressure will be recorded following the application of the capsaicin pain patch, up to or around 15 minutes
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Baseline 12-Hour FastResting baseline will be recorded prior (and on a separate day from) the 12-hour fast, up to or around 5 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, 12-Hour FastSeated blood pressure recordings will occur following a 12-hour fast, up to or around 15 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Seated Baseline, Caffeine ConsumptionResting baseline blood pressure will be recording prior to caffeine consumption, up to or around 5 minutes
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Following Caffeine ConsumptionContinuous blood pressure recordings will occur immediately following caffeine consumption, up to or around 60 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Baseline Prior to Maximal Exercise TestBaseline blood pressure recordings will occur prior to the maximal exercise test, up to or around 5 minutes.
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.
Blood Pressure, Maximal Exercise TestContinuous blood pressure recordings will take place throughout the maximal aerobic exercise test on the treadmill, up to or around 20 minutes
Investigators will collect beat-to-beat blood pressure recordings in all participants before, during, and after the six stressor tests. These cardiovascular perturbations will provide insight into sympathetic nervous system modulation in individuals with Down syndrome compared to those without Down syndrome.

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