Impact of Continuous Positive Airway Pressure Therapy on Bilateral Local Hippocampal Gray Matter Volume in Elderly Patients With Obstructive Sleep Apnea - Study BBBSAS

This study evaluates whether treating severe obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) for approximately 6 months modifies local hippocampal and frontal cortex gray matter volume and blood-brain barrier (BBB) permeability in elderly men. Twenty-five men aged 70 years or older with newly diagnosed, previously untreated severe OSA (apnea-hypopnea index \[AHI\] \> 30) are compared with 25 age- and body-mass-index-matched control men without OSA (AHI \< 10, oxygen desaturation index \< 10). All participants undergo a comprehensive neurocognitive assessment, instrumented gait and balance analysis, blood and urine sampling for systemic inflammatory and aquaporin markers, and a multimodal brain MRI with intravenous Gadolinium injection to quantify BBB permeability and gray/white matter volume. Patients repeat the MRI, cognitive testing, and gait/balance assessment after approximately 6 months of CPAP therapy, once adequate treatment adherence (≥5 hours/night). The main hypothesis is that severe untreated OSA is associated with focal BBB permeability abnormalities in the hippocampus and frontal cortex, and that effective CPAP treatment partially reverses these anatomical and functional changes, together with improvements in executive/memory performance, gait, balance, and systemic inflammation. Results are expected to clarify the neurocognitive impact of OSA in the elderly, help target patients who most need treatment, and identify complementary pharmacological targets.

Inclusion criteria * Affiliated with or entitled to French social security coverage * Informed and signed consent to participate * Newly diagnosed, previously untreated severe obstructive sleep apnea (AHI \> 30) * Male sex * Aged 70 years or older, no upper age limit * Native French speaker, able to complete all study procedures Exclusion criteria * Contraindication to MRI (pacemaker, metallic heart valve, ocular metallic foreign body…) * Contraindication to Gadolinium injection (prior allergic reaction to a contrast agent) * Type 1 or type 2 diabetes * History of stroke or congestive heart failure * Severe chronic renal insufficiency * Chronic respiratory insufficiency requiring oxygen therapy * Daily use of hypnotics, anxiolytics, antidepressants, antipsychotics, or antiepileptics * Sleep-related neurological disorder or chronic insomnia * Known neurodegenerative disease * Central sleep apnea (central AHI \> 15 or more than 5% central events) * Participation in another study that could affect cognitive function or sleepiness