School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, Australia.
Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
Sleep. 2019 Jan 1;42(1). doi: 10.1093/sleep/zsy199.
Obstructive sleep apnea (OSA) is commonly associated with memory impairments. Although MRI studies have found volumetric differences in the hippocampus of people with OSA compared with controls, MRI lacks the spatial resolution to detect changes in the specific regions of the hippocampus that process different types of memory. The present study performed histopathological investigations on autopsy brain tissue from 32 people with OSA (17 females and 15 males) to examine whether the thickness and myelination of the hippocampus and entorhinal cortex (EC) vary as a function of OSA severity. Increasing OSA severity was found to be related to cortical thinning in the molecular layer of the dentate gyrus (r2 = 0.136, p = 0.038), the CA1 (overall, r2 = 0.135, p = 0.039; layer 1, r2 = 0.157, p = 0.025; layer 2, r2 = 0.255, p = 0.003; and layer 3, r2 = 0.185, p = 0.014) and in some layers of the EC (layer 1, r2 = 0.186, p = 0.028; trend in layer 3, r2 = 0.124, p = 0.078). OSA severity was also related to decreased myelin in the deep layers but not the superficial layers of the EC (layer 6, r2 = 0.282, p = 0.006; deep white matter, r2 = 0.390, p = 0.001). Patients known to have used continuous positive airway pressure (CPAP) treatment showed no significant reductions in cortical thickness when compared with controls, suggesting that CPAP had a protective effect. However, CPAP did not protect against myelin loss. The regions of decreased cortical thickness and demyelination are locations of synaptic connections in both the polysynaptic (episodic and spatial) and direct (semantic) memory pathways and may underpin the impairments observed in episodic, semantic, and spatial memory in people with OSA.
阻塞性睡眠呼吸暂停（OSA）通常与记忆障碍有关。尽管 MRI 研究发现 OSA 患者的海马体体积与对照组存在差异，但 MRI 缺乏空间分辨率来检测海马体特定区域处理不同类型记忆的变化。本研究对 32 名 OSA 患者（17 名女性和 15 名男性）的尸检脑组织进行了组织病理学研究，以检查海马体和内嗅皮层（EC）的厚度和髓鞘是否随 OSA 严重程度的变化而变化。研究发现，OSA 严重程度的增加与齿状回分子层（r2 = 0.136，p = 0.038）、CA1（整体，r2 = 0.135，p = 0.039；层 1，r2 = 0.157，p = 0.025；层 2，r2 = 0.255，p = 0.003；层 3，r2 = 0.185，p = 0.014）和 EC 的某些层（层 1，r2 = 0.186，p = 0.028；层 3 的趋势，r2 = 0.124，p = 0.078）的皮质变薄有关。OSA 严重程度也与 EC 深层而不是浅层的髓鞘减少有关（层 6，r2 = 0.282，p = 0.006；深层白质，r2 = 0.390，p = 0.001）。与对照组相比，已知使用持续气道正压通气（CPAP）治疗的患者的皮质厚度没有明显减少，这表明 CPAP 具有保护作用。然而，CPAP 并不能防止髓鞘丢失。皮质厚度和脱髓鞘减少的区域是多突触（情景和空间）和直接（语义）记忆通路中突触连接的位置，可能是 OSA 患者观察到的情景、语义和空间记忆障碍的基础。
