243 Adverse relationships between sleep apnea, white matter integrity and perfusion is attenuated in more physically fit older adults

Abstract

Abstract Introduction White matter (WM) integrity declines with age and is sensitive to vascular risk modifiers, such as exercise. Sleep apnea is believed to contribute to cerebral white matter change via intermittent hypoxia-induced alterations to cerebral blood flow resulting in cerebrovascular shearing. Existing literature highlights the relationships between poor sleep and numerous adverse health outcomes, including risk for cardiovascular disease and dementia. Conversely, exercise seems to have a positive effect on both brain structure and function. Here we examine a potential interaction between sleep apnea severity and cardiorespiratory fitness (characterized by a gender-specific Non-Exercise CardioRespiratory Fitness Measure, NECRFM) as predictors of MRI measures of brain WM integrity and cerebral blood flow (CBF) in a sample of non-demented older adult participants of the Wisconsin Sleep Cohort (WSC). Methods Cross-sectional linear models using data from a subset of 124 WSC participants (50% female; mean age[range]=67.6 [49.6, 85.3]) examined the relationship between sleep apnea severity (apnea-hypopnea index, AHI) and cardiorespiratory fitness in predicting MRI-assessed total WM and lesion volumes, WM hyperintensities (WMHs; a marker of small vessel disease in the brain) and Arterial Spin Labeling (ASL) CBF, controlling for age, sex, BMI, education, and hypertension. Results Greater sleep apnea severity was associated more strongly with both total lesion and WMH loads in less fit compared to more fit persons (p’s<0.05) in the absence of significant differences in total WM volume. Regional perfusion revealed higher CBF in the angular gyrus, middle frontal cortex, and superior frontal gyrus and lower CBF in the anterior cingulate gyrus and the hippocampus of more fit compared to less fit persons (p’s< 0.05), in the absence of differences in mean global perfusion. Conclusion Overall, our results suggest that better general fitness may attenuate negative brain health outcomes related to poor sleep. We highlight an important relationship between brain health and modifiable behavioral factors, namely sleep and fitness, that have the potential to help maintain or improve brain integrity with age. Support (if any) This work was supported by United States National Institutes of Health grants R01AG062167, R01AG058680, R01HL62252, 1R01AG036838 and 1UL1RR025011.