Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal, Canada.
Biol Psychiatry. 2010 Nov 15;68(10):894-902. doi: 10.1016/j.biopsych.2010.02.004. Epub 2010 Mar 31.
Alzheimer's disease is a neurodegenerative disease with progressive cognitive impairments that are likely to affect the compensatory mechanisms and the cerebral activation patterns of the patients.
Functional neuroimaging was used to test the effect of disease severity on the brain activation of persons at risk for Alzheimer's disease and to highlight the process of compensation in some of these individuals. This was done for the verbal learning of either semantically related or semantically unrelated word pairs. Twenty-six persons with mild cognitive impairment (MCI) were separated into two groups, MCI higher-cognition and MCI lower-cognition, with a split-median on their scores for the Mattis Dementia Rating Scale. A group of 14 healthy older adults were matched to the MCI participants.
In both task conditions, MCI higher-cognition activated additional regions, relative to control subjects, in the right ventrolateral and dorsolateral prefrontal brain areas. Additional areas of hyperactivation were found in the right prefrontal area 45 when encoding semantically related word pairs and in the left hippocampus during encoding of unrelated word pairs. In contrast, MCI lower-cognition failed to show additional prefrontal activations when compared with healthy control subjects and showed decreased activation in posterior areas.
These results are in line with compensation occurring at the beginning of the MCI continuum and with the breakdown of compensation in patients experiencing more severe symptoms.
阿尔茨海默病是一种神经退行性疾病，其认知功能逐渐受损，可能会影响患者的代偿机制和大脑激活模式。
使用功能神经影像学来测试疾病严重程度对阿尔茨海默病高危人群大脑激活的影响，并突出这些个体中某些人的补偿过程。这是通过对语义相关或语义不相关的单词对进行言语学习来完成的。将 26 名轻度认知障碍（MCI）患者分为 MCI 高认知和 MCI 低认知两组，根据他们在 Mattis 痴呆评定量表上的得分进行中位数分割。一组 14 名健康的老年成年人与 MCI 参与者相匹配。
在两种任务条件下，MCI 高认知组与对照组相比，在右侧腹外侧和背外侧前额叶脑区激活了更多的区域。在语义相关单词对编码时，在右侧前额叶区域 45 发现了更多的过度激活区域，而在不相关单词对编码时，在左侧海马体发现了更多的过度激活区域。相比之下，与健康对照组相比，MCI 低认知组未能显示出额外的前额叶激活，并且在后部区域显示出激活减少。
这些结果与 MCI 连续体开始时发生的代偿以及症状更严重的患者代偿失败一致。
