Cognitive archaeology: identifying and measuring the presymptomatic phase of dementia

阿尔茨海默病和其他常见的痴呆症病因的发病是一个潜伏的过程，通常对病人、他们的亲属或医生来说是不明显的，直到发生了相当大的脑组织损失。这是因为大脑拥有储备能力，可以用来维持正常的功能水平。人们认为，只有当这种“认知储备”耗尽时，痴呆症才会变得明显。人们有不同的认知储备能力，这可能解释了为什么患有痴呆症的个体之间的预后和进展速度如此不同。了解导致认知储备能力增加的因素是试图控制未来25年痴呆症预期人口增长的重要途径。通过观察痴呆症出现前几十年的语言记录，我们希望能够追踪变化的模式，表明智力损伤的最早迹象是在什么时候、在什么时间过程中出现的。通过将这些测量的差异与身体、社会和人口统计信息相关联，应该揭示与认知储备大小相关的重要因素，在某些情况下，可能是可修改的，因此对阿尔茨海默病和其他晚年神经退行性痴呆的影响的恢复能力。

The onset of Alzheimer’s disease and other common causes of dementia is an insidious process, which typically does not become apparent to a patient, their relatives, or medical practitioners, until considerable brain tissue loss has taken place. This is due to the fact that the brain possesses a reserve capacity, which can be used to contnue normal levels of functioning. It is believed that dementia only becomes apparent when this ‘cognitive reserve’ has been exhausted. People’s have different cognitive reserve capacities, which probably explains why the prognosis, and speed of progression is so variable between individuals with established dementia. Understanding the factors that give rise to a large cognitive reserve capacity represents an important way of trying to control the expected population increase in dementia over the next 25 years. By looking at language records laid down over decades prior to the emergence of dementia, we hope to be able to trace patterns of change that indicate when, and over what time-course, the earliest indications of intellectual impairment occurred. By correlating differences in these measurements with physical, social and demographic information, should reveal important, and in some cases, potentially modifiable, factors associated with the size of the cognitive reserve, and therefore resilience to the effects of Alzheimer’s disease and other later-life neurodegenerative dementias.