Department of Cognition, Development and Educational Psychology, University of Barcelona, Barcelona, Spain.
University of Guadalajara, Jalisco, México.
J Alzheimers Dis. 2021;82(1):421-433. doi: 10.3233/JAD-201301.
Alzheimer's disease (AD) is characterized by progressive deterioration of cognitive functions and may be preceded by mild cognitive impairment (MCI). Evidence shows changes in pupil and vergence responses related to cognitive processing of visual information.
Here we test the hypothesis that MCI and AD are associated with specific patterns in vergence and pupil responses.
We employed a visual oddball task. In the distractor condition (80%of the trials), a blue stimulus was presented whereas in the target condition (20%of trials) it was red. Participants (23 Controls, 33 MCI patients, and 18 AD patients) were instructed to press a button when a target appeared.
Participants briefly converged their eyes 200 ms after stimulus presentation. In controls, this transient peak response was followed by a delay response to targets but not to distractor stimuli. In the patient groups, delay responses to distractors were noticed. Consequently, the differential vergence response was strong in the control group, weak in the MCI group, and absent in the AD group. Pupils started to dilate 500-600 ms after the appearance of a target but slightly contracted after the presentation of a distractor. This differential pupil response was strongest in the AD group.
Our findings support the idea of a role of vergence and pupil responses in attention and reveal altered responses in MCI and AD patients. Further studies should assess the value of vergence and pupil measurements as an objective support tool for early diagnosis of AD.
阿尔茨海默病（AD）的特征是认知功能的进行性恶化，可能先于轻度认知障碍（MCI）。有证据表明，瞳孔和聚散反应的变化与视觉信息的认知处理有关。
本研究旨在检验 MCI 和 AD 与聚散和瞳孔反应特定模式相关的假设。
我们采用了视觉Oddball 任务。在分心条件（80%的试验）下，呈现蓝色刺激，而在目标条件（20%的试验）下呈现红色。参与者（23 名对照组、33 名 MCI 患者和 18 名 AD 患者）被指示在目标出现时按下按钮。
参与者在刺激呈现后 200ms 短暂地会聚他们的眼睛。在对照组中，这种短暂的峰值反应后，对目标有延迟反应，但对分心刺激没有。在患者组中，注意到对分心刺激的延迟反应。因此，在对照组中，差异聚散反应较强，在 MCI 组中较弱，在 AD 组中不存在。瞳孔在目标出现后 500-600ms 开始扩张，但在呈现分心刺激后略有收缩。这种差异的瞳孔反应在 AD 组最强。
我们的研究结果支持了瞳孔和聚散反应在注意力中的作用的观点，并揭示了 MCI 和 AD 患者的异常反应。进一步的研究应该评估聚散和瞳孔测量作为 AD 早期诊断的客观支持工具的价值。
