Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China.
Curr Alzheimer Res. 2020;17(2):168-176. doi: 10.2174/1567205017666200309104033.
Subjective Cognitive Decline (SCD) is the early preclinical stage of Alzheimer's Disease (AD). Previous study provided an invaluable contribution by showing that a tactile angle discrimination system can be used to distinguish between healthy older individuals and patients with mild cognitive impairment and AD. However, that study paid little attention to the relationship between tactile angle discrimination and SCD. Therefore, a means of differentiating Normal Controls (NCs), elderly subjects with SCD, patients with amnestic Mild Cognitive Impairment (aMCI), and AD is urgently needed.
In the present study, we developed a novel tactile discrimination device that uses angle stimulation applied to the index finger pad to identify very small differences in angle discrimination between the NC (n = 30), SCD (n = 30), aMCI (n = 30), and AD (n = 30) groups. Using a three-alternative forced-choice and staircase method, we analyzed the average accuracy and threshold of angle discrimination.
We found that accuracy significantly decreased while thresholds of angle discrimination increased in the groups in the following order: NC, SCD, aMCI, and AD. The area under the receiver operating characteristic curve also indicated that the tactile angle discrimination threshold was better than Mini-Mental State Examination scores in distinguishing NC individuals and SCD patients.
These findings emphasize the importance of tactile working memory dysfunction in explaining the cognitive decline in angle discrimination that occurs in SCD to AD patients and offer further insight into the very early detection of subjects with AD.
主观认知衰退（SCD）是阿尔茨海默病（AD）的早期临床前阶段。先前的研究通过表明触觉角度辨别系统可用于区分健康的老年人与轻度认知障碍和 AD 患者，提供了宝贵的贡献。然而，该研究很少关注触觉角度辨别与 SCD 之间的关系。因此，迫切需要一种能够区分正常对照组（NCs）、有 SCD 的老年受试者、有遗忘型轻度认知障碍（aMCI）和 AD 的患者的方法。
在本研究中，我们开发了一种新型的触觉辨别装置，该装置使用刺激食指垫的角度来识别 NC（n=30）、SCD（n=30）、aMCI（n=30）和 AD（n=30）组之间角度辨别差异非常小。使用三择一强迫选择和阶梯法，我们分析了角度辨别平均准确性和阈值。
我们发现，在以下顺序中，准确性显著降低，而角度辨别阈值增加：NC、SCD、aMCI 和 AD。受试者工作特征曲线下的面积也表明，触觉角度辨别阈值在区分 NC 个体和 SCD 患者方面优于简易精神状态检查分数。
这些发现强调了触觉工作记忆功能障碍在解释 SCD 到 AD 患者的角度辨别认知下降中的重要性，并为 AD 患者的非常早期检测提供了进一步的见解。
