Rush Alzheimer’s Disease Center and Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA.
Neurology. 2012 Apr 10;78(15):1116-22. doi: 10.1212/WNL.0b013e31824f7ff2. Epub 2012 Apr 4.
To test the cognitive dedifferentiation hypothesis that cognitive abilities become increasingly correlated in late life.
Participants are 174 older persons without dementia at the beginning of a longitudinal clinical-pathologic cohort study. At annual intervals for 6 to 15 years prior to death, they completed a battery of cognitive performance tests from which previously established composite measures of episodic memory, semantic memory, working memory, and perceptual speed were derived. At death, there was a uniform neuropathologic assessment and levels of diffuse plaques, neuritic plaques, and neurofibrillary tangles were summarized in a composite measure. Change in the 4 cognitive outcomes was analyzed simultaneously in a mixed-effects model that allowed rate of decline to accelerate at a variable point before death.
On average, cognitive decline before the terminal period was relatively gradual, and rates of change in different cognitive domains were moderately correlated, ranging from 0.25 (episodic memory-working memory) to 0.46 (episodic memory-semantic memory). By contrast, cognition declined rapidly during the terminal period, and rates of change in different cognitive functions were strongly correlated, ranging from 0.83 (working memory-perceptual speed) to 0.89 (episodic memory-semantic memory, semantic memory-working memory). Higher level of plaques and tangles on postmortem examination was associated with faster preterminal decline and earlier onset of terminal decline but not with rate of terminal decline or correlations between rates of change in different cognitive functions.
In the last years of life, covariation among cognitive abilities sharply increases consistent with the cognitive dedifferentiation hypothesis.
检验认知去分化假设，即认知能力在晚年变得越来越相关。
参与者是 174 名在纵向临床病理队列研究开始时没有痴呆的老年人。在死亡前 6 至 15 年的每年间隔时间内，他们完成了一系列认知表现测试，从中得出了先前建立的情景记忆、语义记忆、工作记忆和知觉速度的综合衡量标准。在死亡时，进行了统一的神经病理学评估，并将弥漫性斑块、神经原纤维缠结和神经纤维缠结的水平汇总为一个综合衡量标准。在混合效应模型中同时分析了 4 种认知结果的变化，该模型允许在死亡前的某个可变点加速下降速度。
平均而言，在终末期之前的认知下降相对较缓慢，不同认知领域的变化率中度相关，范围从 0.25（情景记忆-工作记忆）到 0.46（情景记忆-语义记忆）。相比之下，在终末期认知迅速下降，不同认知功能的变化率高度相关，范围从 0.83（工作记忆-知觉速度）到 0.89（情景记忆-语义记忆、语义记忆-工作记忆）。死后检查中斑块和缠结水平较高与较快的终末期前下降和较早的终末期下降起始相关，但与终末期下降速度或不同认知功能变化率之间的相关性无关。
在生命的最后几年，认知能力的变化高度相关，这与认知去分化假设一致。
