White matter tract-specific alterations in male patients with untreated obstructive sleep apnea are associated with worse cognitive function

• Published in: Sleep (New York, N.Y.) N.Y.), 2020-03, Vol.43 (3), p.1
• Main Authors: Koo, Dae Lim, Kim, Hye Ryun, Kim, Hosung, Seong, Joon-Kyung, Joo, Eun Yeon
• Format: Article
• Language: English
• Subjects: Anisotropy; Batteries; Brain - diagnostic imaging; Cognition; Diffusion Tensor Imaging; Humans; Male; Neuropsychological Tests; Sleep apnea; Sleep Apnea, Obstructive - complications; Sleep Apnea, Obstructive - diagnostic imaging; Sleep Disordered Breathing; White Matter - diagnostic imaging
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleep/zsz247

Abstract Study Objectives Neurocognitive impairment is one of the daytime symptoms of obstructive sleep apnea (OSA). We proposed to use tract-specific statistical analysis (TSSA) to investigate whether there are fiber tract abnormalities in OSA, which may be undiscovered using voxel-based approaches, and whether such tract-specific disruptions in brain connectivity are associated with neuropsychological deficits in patients with untreated OSA. Methods We enrolled 38 patients with OSA diagnosed by overnight polysomnography, and 41 healthy sleepers. Fractional anisotropy (FA) and mean diffusivity (MD) maps were obtained from whole-brain diffusion tensor imaging, and TSSA were used to assess regional deficits of white matter tracts. All participants underwent a battery of neuropsychological tests. To evaluate the association between FA values and clinical, polysomnographic, and neuropsychological parameters in the OSA group, permutation-based tests for correlation were performed preceding cluster-based statistics. Results Compared to healthy controls, patients with OSA showed decreased values of FA in the left and right anterior thalamic radiations, and right uncinate fasciculus (UNC) (p < 0.001, p = 0.005, and p = 0.008, respectively). A lower score of digit span backward was associated with lower FA values of right UNC in the OSA group (p = 0.023). The Rey Complex Figure Test copy score revealed a positive correlation with FA values in the right UNC (p = 0.010). Conclusions The TSSA method indeed identified previously unrevealed tract-specific disruptions in OSA. Furthermore, reduced FA values in the frontal lobe portion of the right UNC which has been known to be involved in working memory function were significantly associated with lower cognitive performance in patients with untreated OSA.