Daffner K R, Rentz D M, Scinto L F, Faust R, Budson A E, Holcomb P J
Brigham Behavioral Neurology Group and Laboratory of Higher Cortical Functions, Division of Cognitive and Behavioral Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Neurology. 2001 May 22;56(10):1377-83. doi: 10.1212/wnl.56.10.1377.
Patients with mild to moderate AD often are apathetic and fail to attend to novel aspects of their environment.
To investigate the mechanisms underlying these changes by studying the novelty P3 response that measures shifts of attention toward novel events.
While event-related potentials were recorded, mildly impaired AD patients and matched normal controls (NC) viewed line drawings that included a repetitive background stimulus, an infrequent target stimulus, and infrequent novel stimuli. Subjects controlled how long they viewed each stimulus by pressing a button. This served as a measure of their allocation of attention. They also responded to targets by depressing a foot pedal. Patients did not differ from NC in age, education, estimated IQ, or mood but were judged by informants to be more apathetic.
P3 amplitude to novel stimuli was significantly smaller for AD patients than NC. However, P3 amplitude to target stimuli did not differ between groups. For NC, P3 response to novel stimuli was much larger than to background stimuli. In contrast, for patients with AD, there was no difference in P3 response to novel vs background stimuli. Although NC spent more time looking at novel than background stimuli, patients with AD distributed their viewing time evenly. Remarkably, for patients with AD, the amplitude of the novelty P3 response powerfully predicted how long they would spend looking at novel stimuli (R2 = 0.52) and inversely correlated with apathy severity.
The decreased attention to novel events exhibited by patients with AD cannot be explained by a nonspecific reduction in their attentional abilities. The novelty P3 response is markedly diminished in mild AD, at a time when the target P3 response is preserved. The disruption of the novelty P3 response predicts diminished attention to novel stimuli and is associated with the apathy exhibited by patients with AD.
轻至中度阿尔茨海默病（AD）患者常表现出冷漠，对周围环境的新事物缺乏关注。
通过研究测量对新事件注意力转移的新奇P3反应，探讨这些变化背后的机制。
在记录事件相关电位时，轻度受损的AD患者和匹配的正常对照（NC）观看包含重复背景刺激、罕见目标刺激和罕见新奇刺激的线条图。受试者通过按按钮控制观看每个刺激的时间，以此作为注意力分配的一种测量方法。他们还通过踩脚踏板对目标做出反应。患者在年龄、教育程度、估计智商或情绪方面与NC无差异，但据知情者判断，患者更为冷漠。
AD患者对新奇刺激的P3波幅明显小于NC。然而，两组对目标刺激的P3波幅无差异。对于NC，对新奇刺激的P3反应比对背景刺激的大得多。相比之下，对于AD患者，对新奇刺激和背景刺激的P3反应没有差异。尽管NC看新奇刺激的时间比看背景刺激的时间长，但AD患者的观看时间分布均匀。值得注意的是，对于AD患者，新奇P3反应的波幅有力地预测了他们看新奇刺激的时间长短（R2 = 0.52），且与冷漠严重程度呈负相关。
AD患者对新事件注意力下降不能用其注意力能力的非特异性降低来解释。在轻度AD中，当目标P3反应保持时，新奇P3反应明显减弱。新奇P3反应的破坏预示着对新奇刺激的注意力下降，并与AD患者表现出的冷漠有关。
