Sleep-disordered breathing (SDB) in cognitively healthy older adults is associated with brain changes typically seen in Alzheimer disease (AD), new research indicates. Mounting evidence suggests that SDB increases the risk of AD, but the brain mechanisms underlying the link remains unclear. To investigate, Dr. Gael Chetelat of INSERM, in Caen, France, and the French Medit-Ageing Research Group, analyzed data from 127 cognitively unimpaired adults (mean age, 69 years; 63% women); 96 with SDB and 31 without SDB. The presence of SDB was associated with significantly greater amyloid burden, gray-matter volume, perfusion, and metabolism in the posterior cingulate cortex and precuneus, brain regions typically involved in AD, the researchers report. "Interestingly, greater amyloid burden was robustly associated with the severity of hypoxia. Neither SDB severity nor SDB-associated brain changes were associated with cognitive performance, self-reported cognitive and sleep difficulties, and symptoms of sleepiness," they note in JAMA Neurology. The results, they say, suggest that older adults with SDB may have "silent brain changes, including increased amyloid deposition, which may propagate with time and explain why they are more at risk of developing Alzheimer clinical syndrome." Key strengths of the analysis include multimodal assessment of brain integrity and detailed cognitive assessment in a large group of older adults with intact cognitive function. However, its cross-sectional design precludes assessment of the causal associations between SDB and brain changes. "Longitudinal studies are needed to investigate whether these early SDB-associated brain changes will progress to neurodegeneration and cognitive deficits," the researchers conclude. The study had no commercial funding and the authors have no relevant disclosures. Dr. Chetelat did not respond to a request for comment by press time. —Reuters Staff Source
