Sleep-disordered breathing linked to brain aging in Hispanic, Latino adults

Key takeaways:

• In Hispanic and Latino adults, every added sleep disruption was linked to increased hippocampal volume.
• Lower oxygen levels during sleep were linked to increased white matter hyperintensity volumes.

Sleep-disordered breathing and worse oxygenation were linked to larger hippocampal volumes a decade later in Hispanic and Latino adults, according to a study published in Neurology, the medical journal of the American Academy of Neurology.

Lower oxygen levels during sleep were also associated with increased white matter hyperintensity volumes, researchers found.

“Both brain shrinkage and brain growth can harm memory and thinking by disrupting normal brain functions, increasing the risk of cognitive decline and dementia,” Alberto R. Ramos, MD, MS, FAAN, FAASM, of the department of neurology at the Miller School of Medicine at University of Miami, said in a press release.

Hispanic and Latino adults are twice as likely to develop Alzheimer’s disease and related dementias (ADRDs) and more likely to develop sleep-disordered breathing (SDB) compared with white adults, according to the researchers. Previous research has shown an association between SDB, including sleep apnea, and brain health, but results have been mixed and data concerning Hispanic and Latino adults have been limited.

This inspired Ramos and colleagues to evaluate the prospective association between SBD and brain volumes in a cohort of 2,150 adults aged 35 to 85 years (mean age, 67.6 years; BMI, 29.7 mg/kg²; 58.3% women) who had participated in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a community-based prospective cohort study that included multiple metropolitan cities (Bronx, Chicago, Miami and San Diego) to assess sociocultural and cardiovascular risk factors in a diverse population (n = 16,415), and The Study of Latinos Investigation of Neurocognitive Aging (SOL-INCA; n = 6,377), an ancillary study of HCHS/SOL.

At baseline, participants were given an at-home sleep apnea testing kit that was used for a single night without supervision. The test measured respiratory event index (REI), which quantifies the mean number of respiratory obstructions of 3% oxygen desaturation per hour, and continuous oxygenation levels. Approximately 10 years later, participants underwent neuroimaging to obtain total brain, gray matter, white matter hyperintensity (WMH) and hippocampal volumes.

Of the cohort, 56% had an REI score of less than five, 28% had a score between five and 15 and 16% had a score greater than 15. Participants with a higher REI were older, had a higher BMI, more often had hypertension and were more likely to be men.

After adjusting for age, gender, hypertension, insurance access and other factors, Ramos and colleagues found that each additional sleep disruption was associated with increased hippocampal volume of 0.006 cm³ (P < .05). Compared with participants with an REI less than five, participants with an REI greater than 15 had larger hippocampal volumes by 0.24 cm³ (P < .01).

Additionally, the researchers found that lower oxygen levels during sleep were linked to enlarged hippocampal volume and increased white matter hyperintensity volume. These findings remain consistent regardless of age and gender.

Ramos and colleagues noted several limitations to this study, including their inability to obtain participant polysomnograms, lack of health insurance among HCHS/SOL participants and limited generalizability to other ethnicities and races.

“Our findings highlight the complex relationships between sleep health and brain aging and show there is a need for longer studies that follow people beginning in middle age or earlier,” Ramos said in the release. “A clear understanding of how brain volume is affected by sleep apnea and other sleep disorders is essential so people can receive early and effective treatment, especially in people who may be at higher risk for dementia.”

Reference:

• Sleep apnea linked to changes in the brain https://medicalxpress.com/news/2024-12-apnea-linked-brain.html. Published Dec. 18, 2024. Accessed Dec. 18, 2024.