###### Abstract  
We aim to determine the sleep correlates of age-related brain loss in a sample of middle-aged to older males with obstructive sleep apnea (OSA). We recruited consecutive treatment naive male patients with moderate to severe OSA from January to November of 2019. We excluded participants if they had dementia, stroke or heart disease. We collected demographic variables and vascular risk factors. We also obtained the insomnia severity index, the Epworth sleepiness scale and the Pittsburgh sleep quality index. We also obtained computerized neurocognitive testing with the go-no-go response inhibition test, Stroop interference test, catch game test, staged information processing speed test, verbal memory test and non-verbal memory test. We derived age and education adjusted domain-specific \(Z\)-scores for global cognition, memory, attention, processing speed and executive function. We used brain MRI T1-weighted images to derive total hippocampal and gray matter volumes. Partial correlations evaluated associations between variables from sleep questionnaires (e.g., insomnia severity index score), and polysomnographic variables (the apnea-hypopnea index, average oxygen levels during sleep) with cognitive domains and brain volumes. We examined 16 participants with an age range of 40-76 years, 73% Hispanic/Latino. The mean apnea-hypopnea index was 48.9 \(\pm\) 25.5 and average oxygen saturation during sleep was 91.4% \(\pm\) 6.9%. Hypertension was seen in 66% and diabetes mellitus in 27%. We found that the insomnia severity index score and average oxygen levels during sleep had the strongest correlations with brain volumes and cognition. These preliminary findings may aid in developing future strategies to improve age-related brain loss in patients with OSA.  
sleep apnea; hypoxemia; cognitive; brain health; MRI +
Footnote †: journal: Medical  
increased risk for age-related cognitive decline and brain loss [19]. Therefore, we aimed to evaluate if the insomnia severity index was associated with cognitive and neuroimaging correlates of brain loss in OSA [20].  
Structural brain characteristics may be indicative of neuronal injury and neurodegeneration that could precede the clinical deterioration commonly observed in AD. Recent use of advanced imaging techniques provides detailed information about the rate of brain tissue loss in specific brain regions associated with AD, such as the hippocampus [21,22]. There is limited data of symptom specific associations between the insomnia severity index and these markers of brain health in a sample of OSA patients. In this pilot-study we examined the feasibility of obtaining cognitive and neuroimaging markers of brain health in a diverse sample of middle-aged to older males from South Florida that include a large proportion of Hispanic/Latino adults. We assessed brain volumes and cognitive performance in newly diagnosed OSA patients [23]. For this analysis, we aimed to characterize the magnetic resonance imaging brain volumes and cognitive domains that correlate with the insomnia severity index in patients with OSA. More specifically, we tested the hypothesis that greater scores in the insomnia severity index, OSA severity (apnea-hypopnea index (AHI) and measures of nocturnal oxygenation (e.g., average oxygen levels during sleep) are associated with poorer cognitive function (global cognition, executive function, memory and processing speed) and greater global brain tissue loss in AD susceptible regions.