Obstructive Sleep Apnea Severity Affects Amyloid Burden in Cognitively Normal Elderly. A Longitudinal Study.

Area of Science:

• Neurology
• Sleep Medicine
• Gerontology

Background:

• Obstructive sleep apnea (OSA) is increasingly recognized as a potential risk factor for cognitive decline, including Alzheimer's disease.
• The specific impact of OSA severity on the longitudinal progression of Alzheimer's disease biomarkers remains less understood.

Purpose of the Study:

• To investigate the association between the severity of obstructive sleep apnea and the longitudinal increase in amyloid burden among cognitively normal elderly individuals.
• To test the hypothesis that greater OSA severity correlates with accelerated amyloid deposition in the brain.

Main Methods:

• A 2-year prospective longitudinal study involving healthy, cognitively normal elderly volunteers (aged 55-90).
• Measurement of cerebrospinal fluid (CSF) amyloid-beta (Aβ) using ELISA and brain amyloid deposition via Pittsburgh Compound B (PiB) positron emission tomography (PET) scans.
• Assessment of OSA severity using home sleep recording devices, analyzing indices like AHIall and AHI4%.

Main Results:

• Higher severity of OSA, indicated by AHIall and AHI4% indices, was significantly associated with the annual rate of change in CSF Aβ42 levels.
• No significant association was found between OSA severity and increases in brain amyloid deposition (AD-PiB-mask), potentially due to the study's small sample size, although a trend was observed.

Conclusions:

• In cognitively normal elderly individuals, OSA is associated with biomarkers indicating increased amyloid burden over a 2-year period.
• Sleep fragmentation and intermittent hypoxia resulting from OSA are proposed as potential mechanisms driving amyloid accumulation.
• These findings suggest that interventions targeting OSA could be beneficial in preventing or slowing amyloid buildup, potentially mitigating Alzheimer's disease risk.