Zhongnan Hospital of Wuhan University, No. 169 Donghu Road, Wuchang District, Wuhan City 430071, Hubei Province, China.
Sleep Breath. 2013 May;17(2):573-82. doi: 10.1007/s11325-012-0723-1. Epub 2012 Jun 7.
The impact of different severities of obstructive sleep apnea (OSA) on cognition has not well been documented. Neuroglobin, a recently discovered vertebrate protein, shows a neuroprotective function to modulate hypoxic-ischemic brain injury. This study investigated the cognitive function of patients with varying OSA severities and intended to explore the relationship between levels of neuroglobin in serum and cognitive deficits of OSA.
Sixty Chinese adults aged 18-59 years old were enrolled and categorized into four groups based on apnea-hypopnea index (AHI): primary snoring (n = 7), mild (n = 13), moderate (n = 20), and severe (n = 20) OSA groups. Computer-based neurocognitive tests (including calculation, memory, and attention) and Epworth sleepiness scale were administered before polysomnographic monitoring, and blood sample was taken the next morning. Concentrations of serum neuroglobin were measured using ELISA.
No significant difference was observed in cognitive function regardless of OSA severities, but patients with moderate and severe OSA presented significantly more sleepiness than patients with primary snoring and mild OSA. Memory significantly correlated with time spent with oxygen saturation below 90 % during nighttime (T < 90 %), as well as oxygen desaturation index, AHI, or NREM sleep. Calculation correlated significantly with sleepiness and respiratory arousal index. Levels of neuroglobin in serum of patients with varying OSA severities were significant elevated than that of patients with primary snoring. No relationship was found between the neurobehavioral ability index of neurocognitive tests and serum neuroglobin concentrations after controlling for gender, age, and BMI, whereas the unique association between levels of neuroglobin in serum and the scores of auditory digit span test was noted.
Our findings suggest that different neurocognitive domains might specifically correlate to either sleepiness or hypoxemia. Changes of concentrations of neuroglobin in serum may possibly be used as an indicator to monitor the brain damage of OSA. Further investigations are needed to explore the relationship between regulation of neuroglobin in serum and severity of brain damage in OSA.
不同严重程度阻塞性睡眠呼吸暂停（OSA）对认知的影响尚未得到很好的记录。神经球蛋白是一种最近发现的脊椎动物蛋白，具有调节缺氧缺血性脑损伤的神经保护功能。本研究调查了不同 OSA 严重程度患者的认知功能，并旨在探讨血清中神经球蛋白水平与 OSA 认知缺陷之间的关系。
纳入 60 名年龄在 18-59 岁的中国成年人，根据呼吸暂停低通气指数（AHI）分为四组：单纯性打鼾（n=7）、轻度（n=13）、中度（n=20）和重度（n=20）OSA 组。在进行多导睡眠图监测之前，进行计算机神经认知测试（包括计算、记忆和注意力）和 Epworth 嗜睡量表评估，并于次日清晨采集血样。采用 ELISA 法测定血清神经球蛋白浓度。
无论 OSA 严重程度如何，认知功能均无显著差异，但中重度 OSA 患者的嗜睡程度明显高于单纯性打鼾和轻度 OSA 患者。记忆与夜间氧饱和度低于 90%的时间（T<90%）、氧减指数、AHI 或 NREM 睡眠显著相关。计算与嗜睡和呼吸唤醒指数显著相关。与单纯性打鼾患者相比，不同 OSA 严重程度患者的血清神经球蛋白水平显著升高。控制性别、年龄和 BMI 后，神经认知测试的神经行为能力指数与血清神经球蛋白浓度之间无相关性，但发现血清神经球蛋白水平与听觉数字跨度测试评分之间存在独特的相关性。
我们的研究结果表明，不同的神经认知域可能与嗜睡或低氧血症有特定的相关性。血清神经球蛋白浓度的变化可能可作为监测 OSA 脑损伤的指标。需要进一步研究来探讨血清中神经球蛋白的调节与 OSA 脑损伤严重程度之间的关系。
