0510 Altered functional connectivity of the ascending reticular activating system in obstructive sleep apnea

Abstract

Abstract Introduction Recurrent arousals in obstructive sleep apnea (OSA) may lead to alteration in functional connection involving in the ascending reticular activating system (ARAS). We aimed to evaluate resting-state functional connectivity (FC) between eight ARAS nuclei and 105 cortical/subcortical regions in OSA patients and matched controls. Methods Total of 50 patients with moderate to severe OSA and 20 controls without OSA underwent overnight polysomnography (PSG) and resting-state functional magnetic resonance imaging in the following morning. Seed to voxel analysis of ARAS-cortical FC was compared between the patients and controls. The ARAS nuclei included dorsal and median raphe nucleus, locus coeruleus (LC), laterodorsal tegmental nucleus (LDTg), pedunculopontine tegmental nucleus, pontine nucleus oralis, parabrachial complex, and ventral tegmental area (VTA). Correlations between average FC values of significant clusters and PSG parameters were calculated in the patients. Results FC values in the three of the ARAS nuclei (LC, LDTg, and VTA) were significantly different between the group. The FC value between the LC and the precuneus cortex, posterior cingulate gyrus, and right lateral occipital cortex (LOC) was increased in OSA patients compared to the controls. The FC value between the LDTg and right LOC was enhanced, but the FC one between the VTA and right LOC was reduced in the patients. The average LC-cortical FC values positively correlated with the arousal index(r=0.282, p=0.047), apnea index(r=0.325, p=0.021), or apnea-hypopnea index (r=0.302, p=0.033) in OSA patients. Conclusion The results of this study support alteration in ARAS-cortical FC in OSA patients. Degree of the noradrenergic LC-cortical FC may be related to arousal or OSA severity in the patients. Support (if any)