Background: Visual delta event-related (ERO) and evoked oscillations (EO) of Alzheimer patients (AD) are different than healthy. In the present study, the analysis is extented to include auditory ERO and EO in AD. The rationale is to reveal whether the auditory ERO delta responses are also reduced, and whether this is a general phenomenon in Alzheimer patients upon applying stimuli with cognitive load.Methods: Thirty-four mild AD subjects (17 de-novo and 17 medicated (cholinergic)) and seventeen healthy controls were included. Auditory oddball paradigm and sensory auditory stimuli were applied to the subjects. Oscillatory responses were analyzed by measuring maximum amplitudes in delta frequency range (0.5–3.5 Hz).Results: Auditory delta ERO (0.5–3.5 Hz) responses of healthy controls were higher than either de-novo AD or medicated AD group, without a difference between two AD subgroups. Furthermore, the auditory EO after presentation of tone bursts yielded no group difference.Conclusion: Our findings imply that delta ERO is highly unstable in AD patients in comparison to age-matched healthy controls only during the cognitive paradigm. Our results favor the hypothesis that neural delta networks are activated during cognitive tasks and that the reduced delta response is a general phenomenon in AD, due to cognitive impairment.

中文翻译：

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阿尔茨海默病中听觉 delta 事件相关的振荡反应降低。

背景：阿尔茨海默病患者 (AD) 的视觉 delta 事件相关 (ERO) 和诱发振荡 (EO) 与健康人不同。在本研究中，分析扩展到包括 AD 中的听觉 ERO 和 EO。其基本原理是揭示听觉 ERO delta 反应是否也减少，以及这是否是阿尔茨海默病患者在应用具有认知负荷的刺激后的普遍现象。方法：包括34 名轻度 AD 受试者（17 名从头开始和 17 名药物（胆碱能））和 17 名健康对照。将听觉古怪范式和感官听觉刺激应用于受试者。通过测量 delta 频率范围 (0.5–3.5 Hz) 中的最大幅度来分析振荡响应。结果：健康对照的听觉 delta ERO (0.5–3.5 Hz) 反应高于从头 AD 或药物 AD 组，两个 AD 亚组之间没有差异。此外，在出现音调爆发后的听觉 EO 没有产生组差异。结论：我们的研究结果表明，仅在认知范式期间，与年龄匹配的健康对照相比，AD 患者的 delta ERO 高度不稳定。我们的结果支持以下假设：神经 delta 网络在认知任务期间被激活，并且由于认知障碍，delta 反应减少是 AD 中的普遍现象。