Risk of Alzheimer's disease in obstructive sleep apnea syndrome: Amyloid-β and tau imaging

Background: An association between obstructive sleep apnea (OSA) and Alzheimer's disease has been suggested but little is known about amyloid-β and tau deposition in this syndrome. Objective: To determine amyloid and tau burden and cognitive function in OSA in comparison with those without a diagnosis of OSA. Methods: The status of OSA was determined by asking participants about history of polysomnographic diagnosis of OSA and the use of Continuous Positive Airway Pressure (CPAP). A comprehensive neuropsychological battery measured cognitive function. Positron emission tomography (PET) was used to measure standardized uptake value ratio (SUVR) of 18 F-florbetaben and 18 F-AV1451, to quantify amyloid and tau burden. Results: 119 male Vietnam veterans completed assessment. Impairment in visual attention and processing speed and increased body mass index (BMI) were seen in subjects with OSA compared with those without a diagnosis OSA. The cortical uptake of 18 F-florbetaben was higher in the OSA group than in the control group (SUVR: 1.35±0.21 versus 1.27±0.16, p=0.04). There were more apolipoprotein E ϵ4 allele (APOE ϵ4) carriers in the OSA group than in the control group. In multilinear regression analysis, the significance of OSA in predicting 18 F-florbetaben uptake remained independent of age and vascular risk factors but not when BMI or APOE ϵ4 was adjusted. The reported use of CPAP (n=14) had no effect on cognitive or amyloid PET findings. There was no significant difference in 18 F-AV1451 uptake between the two groups. Conclusions: Obstructive sleep apnea is associated with Alzheimer's disease pathology, but this relationship is moderated by APOE ϵ4 and BMI.