Sympathetic hyperactivity mediates the association between obstructive sleep apnea and hypertension: age effect

Area of Science:

• Cardiology
• Sleep Medicine
• Hypertension Research

Background:

• Obstructive sleep apnea (OSA) is linked to hypertension, particularly in younger and middle-aged individuals.
• Sympathetic nervous system overactivity is a proposed mechanism underlying this association.
• Age may influence the relationship between OSA, sympathetic activity, and hypertension.

Purpose of the Study:

• To investigate whether sympathetic hyperactivity mediates the association between OSA and hypertension.
• To determine if age moderates the effect of OSA on sympathetic activity and blood pressure.

Main Methods:

• Defined OSA using apnea-hypopnea index (AHI) ≥5 events/hour from polysomnography.
• Assessed hypoxic severity using time under 90% oxygen (T90).
• Measured sympathetic activity via 24-hour urinary norepinephrine and blood pressure.

Main Results:

• Increased AHI and T90 correlated with higher norepinephrine levels in young/middle-aged OSA patients, but not older adults.
• OSA severity (AHI, T90) was associated with higher blood pressure in younger/middle-aged individuals, but not older ones.
• Sympathetic hyperactivity mediated 7.67–13.41% of the OSA-hypertension association in younger/middle-aged patients.

Conclusions:

• Sympathetic hyperactivity mediates the link between OSA and hypertension in individuals under 50.
• The influence of OSA on hypertension via sympathetic pathways is significantly diminished in older adults.