Speech comprehension in noisy environments depends on central auditory functions, which are vulnerable in Alzheimer's disease (AD). Binaural processing exploits two ear sounds to optimally process degraded sound information; its characteristics are poorly understood in AD. We studied behavioral and electrophysiological alterations in binaural processing among 121 participants (AD = 27; amnestic mild cognitive impairment [aMCI] = 33; subjective cognitive decline [SCD] = 30; cognitively normal [CN] = 31). We observed impairment of binaural processing in AD and aMCI, and detected a U-shaped curve change in phase synchrony (declining from CN to SCD and to aMCI, but increasing from aMCI to AD). This improvement in phase synchrony accompanying more severe cognitive stages could reflect neural adaptation for binaural processing. Moreover, increased phase synchrony is associated with worse memory during the stages when neural adaptation apparently occurs. These findings support a hypothesis that neural adaptation for binaural processing deficit may exacerbate cognitive impairment, which could help identify biomarkers and therapeutic targets in AD.

中文翻译：

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阿尔茨海默病的双耳处理缺陷和认知障碍

嘈杂环境中的语音理解取决于中枢听觉功能，这在阿尔茨海默病 (AD) 中很脆弱。双耳处理利用两个耳朵的声音来优化处理退化的声音信息；它的特点在 AD 中知之甚少。我们研究了 121 名参与者的双耳处理的行为和电生理变化（AD = 27；遗忘性轻度认知障碍 [aMCI] = 33；主观认知衰退 [SCD] = 30；认知正常 [CN] = 31）。我们观察到 AD 和 aMCI 中的双耳处理受损，并检测到相位同步中的 U 形曲线变化（从 CN 下降到 SCD 和 aMCI，但从 aMCI 到 AD 增加）。伴随更严重的认知阶段的相位同步的这种改进可能反映了双耳处理的神经适应。而且，在明显发生神经适应的阶段，增加的相位同步与较差的记忆有关。这些发现支持了一个假设，即双耳处理缺陷的神经适应可能会加剧认知障碍，这可能有助于识别 AD 中的生物标志物和治疗靶点。