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Sleep-Disordered Breathing Leads to Brain Changes Generally Found in Alzheimer Disease

Sleep-disordered breathing (SDB) in older adults who were not cognitively impaired led to changes in Alzheimer disease-sensitive brain areas, particularly the precuneus and the posterior cingulate cortex, a cross-sectional study of community-dwelling individuals found.

Participants with sleep-disordered breathing (SDB) demonstrated greater metabolism, gray matter volume, perfusion, and amyloid burden, overlapping primarily over the precuneus and posterior cingulate cortex, reported Claire Andre, PhD, of Normandie Universite in Caen, France, and colleagues on March 23 in JAMA Neurology.

They found no association between self-reported sleep and cognitive difficulties, cognition, or excessive daytime sleepiness symptoms, however.

These data "might explain why sleep-disordered breathing is associated with an increased risk for developing Alzheimer clinical syndrome at a younger age," they added.

"Our findings highlight the need to treat sleep disorders in the older population, even in the absence of cognitive or behavioral manifestations," the researchers wrote.

Efforts are underway to explore the mechanisms behind the relationship between dementia risk and SBD, as well as the brain changes associated with SDB, the authors noted. Other investigations have reported SDB-related increases and decreases in cortical thickness or gray matter volume in numerous brain regions including parietal, temporal and frontal areas, they pointed out.

The researchers noted, however, that the findings on SDB and Alzheimer's pathology—related to tau and amyloid levels in the cerebrospinal fluid and blood—have been inconsistent. Some cross-sectional PET studies have shown greater amyloid burden in association with SDB, for example, while others do not report a significant association, Dr. Andre and colleagues wrote.

For the current study, the researchers assessed 127 community-dwelling older adults who were cognitively unimpaired at baseline. The cohort was 63 percent female, and their mean age was 69.1 years.

The researchers used information from the Age-Well randomized clinical trials of the Medit-Ageing European project, collected between 2016 and 2018 at Cyceron Center in Caen, France. Community-dwelling older adults were evaluated for eligibility and were enrolled in the Age-Well clinical trial if they were willing to participate and did not meet cognitive or medical exclusion criteria.  Participants were included if they completed a MRI, polysomnography, a detailed neuropsychological evaluation, and fluorodeoxyglucose and florbetapir PET scans were included in the assessment. Participants were classified as having SDB based on an apnea-hypopnea index threshold of 15 events an hour.

Limitations of the study include its cross-sectional design, which did not allow for the evaluation of the causal relationship between brain changes and SDB.

"Longitudinal studies are needed to investigate whether these early SDB-associated brain changes will progress to neurodegeneration and cognitive deficits," the investigators concluded.

Disclosures: Dr. Andre received research funding by Institut National de la Santé et de la Recherche Médicale, Région Normandie, and the Fonds Européen de Développement Régional.

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