Exploring Sympathetic Nervous System Function in Individuals With Down Syndrome

Down syndrome (DS), the most common genetic cause of intellectual disability, is associated with widespread organ dysfunction, including abnormalities in the autonomic nervous system (ANS). The ANS regulates critical functions such as heart rate (HR) and blood pressure (BP), both essential for maintaining homeostasis and supporting physical activity. Individuals with DS often exhibit blunted HR responses to exercise-typically \~30 beats per minute below expected levels-suggesting reduced sympathetic nervous system (SNS) activity. The SNS governs rapid changes in HR and BP during stress by releasing catecholamines: epinephrine (from the adrenal medulla) and norepinephrine (from sympathetic nerve endings). Despite its importance, SNS function has not been comprehensively assessed among individuals with DS. This study addresses a critical knowledge gap by evaluating SNS responses to physiological stressors in individuals with DS. The investigators will measure beat-to-beat HR and BP, along with plasma catecholamine levels, in response to sympathetic activation, comparing individuals with DS to age- and sex-matched controls. Understanding the mechanisms of SNS dysfunction in DS is vital, as it likely underlies reduced exercise capacity and contributes to broader clinical challenges. These insights may guide targeted interventions to improve cardiovascular function, physical capacity, and overall quality of life in this understudied population.

NCT Number	NCT07238465
Lead Sponsor	University of Colorado, Denver Collaborators: National Institute on Aging (NIA), Linda Crnic Institute for Down Syndrome, GLOBAL Down Syndrome Foundation, University of Colorado Colorado Clinical and Translational Sciences Institute
Conditions	Down Syndrome, Autonomic Dysfunction
Enrollment	200 participants
Start Date	2026-04-06
Primary Completion	2028-12 (estimated)
Study Completion	2029-12 (estimated)
Updated on ClinicalTrials.gov	2026-05-04