Association between sleep-disordered breathing and MRI-based brain iron content

Abstract

Introduction: Sleep-disordered breathing (SDB) is associated with dementia. Increased brain iron accumulation has been suggested as a biomarker of neurodegeneration. Objectives: To investigate the link between SDB and brain iron content. We hypothesized that specific brain structures, such as hippocampus, basal ganglia, and frontoparietal cortex, will demonstrate higher iron levels in participants with SDB. Methods: We included participants of the CoLaus|PsyCoLaus population-based study who underwent polysomnography and brain MRI (N=776). We studied the association between SDB markers and MRI-based quantification of brain iron content using flat maps of transverse relaxation rate R2* whilst adjusting for the effects of age, sex, and cardiovascular risk factors. Results: Mean oxygen saturation during sleep was associated with iron content in neocortex (B=-0.061; p=0.001), caudate (B=-0.193; pl0.001), pallidum (B=-0.261; p=0.011), and putamen (B=-0.257; pl0.001). Sleep time with oxygen saturation l90% was associated with iron content in caudate (B=0.020; p=0.004), pallidum (B=0.039; p=0.020), and putamen (B=0.027; p=0.015). Apnea-hypopnea index and oxygen desaturation index were associated with iron content in neocortex (B=0.006; p=0.004, and B=0.007; p=0.005) and pallidum (B=0.038; p=0.002, and B=0.040; p=0.004). Variables of sleep architecture - sleep efficiency, slow wave sleep, wake after sleep onset, arousal index - did not show any association with brain iron content. Conclusions: Sleep-related hypoxemia is associated with increased iron accumulation in neocortex and basal ganglia. Our findings hint towards the usefulness of MRI-based iron quantification as a biomarker of SDB-related brain pathology.