Sleep duration and brain MRI measures: Results from the SOL-INCA MRI study

INTRODUCTION: Sleep duration has been associated with dementia and stroke. Few studies have evaluated sleep pattern–related outcomes of brain disease in diverse Hispanics/Latinos. METHODS: The SOL-INCA (Study of Latinos-Investigation of Neurocognitive Aging) magnetic resonance imaging (MRI) study recruited diverse Hispanics/Latinos (35–85 years) who underwent neuroimaging. The main exposure was self-reported sleep duration. Our main outcomes were total and regional brain volumes. RESULTS: The final analytic sample included n = 2334 participants. Increased sleep was associated with smaller brain volume (β_{total_brain} = −0.05, p < 0.01) and consistently so in the 50+ subpopulation even after adjusting for mild cognitive impairment status. Sleeping >9 hours was associated with smaller gray (β_{combined_gray} = −0.17, p < 0.05) and occipital matter volumes (β_{occipital_gray} = −0.18, p < 0.05). DISCUSSION: We found that longer sleep duration was associated with lower total brain and gray matter volume among diverse Hispanics/Latinos across sex and background. These results reinforce the importance of sleep on brain aging in this understudied population. Highlights: Longer sleep was linked to smaller total brain and gray matter volumes. Longer sleep duration was linked to larger white matter hyperintensities (WMHs) and smaller hippocampal volume in an obstructive sleep apnea (OSA) risk group. These associations were consistent across sex and Hispanic/Latino heritage groups.