Sleep-Disordered Breathing Associated with Brain Atrophy in Amyloid-Positive, Cognitively Unimpaired Individuals

Research published in Neurology has identified an association between sleep-disordered breathing (SDB), such as sleep apnea, and atrophy of the medial temporal lobe (MTL) in amyloid-positive, cognitively unimpaired individuals. The entorhinal cortex and hippocampus specifically showed reduced gray matter in female amyloid-positive individuals, increasing with severity of SDB.

The study (NCT02977819) was conducted in 122 participants aged older than 65 who were in the Medit-Aging European Project Age-Well randomized controlled trial. The participants underwent a sleep study (polysomnography), positron emission tomography (PET) to detect amyloid, and MRI to evaluate atrophy in MTL regions. SDB severity was assessed according to apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and respiratory microarousals index (RMI). Researchers conducted multiple linear regressions to statistically analyze associations between MTL atrophy, amyloid presence, and SDB severity.

AHI and amyloid status were related most significantly in the entorhinal cortex, hippocampus, subiculum, and dentate gyrus. Only amyloid-positive participants showed a relationship between AHI and gray matter changes in these MTL regions. Greater AHI was associated with gray matter volume loss in different MTL regions compared to ODI, while RMI was not associated with gray matter volume. The relationship between SDB severity and MTL gray matter volume was present only in female participants.

SDB is widely prevalent in older adults, is underdiagnosed, and in previous research, has been shown to be associated with greater amyloid deposition in the brain.