Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.
The Irish Longitudinal Study on Ageing, Trinity College Dublin, Dublin, Ireland.
Alzheimers Res Ther. 2021 Jul 12;13(1):128. doi: 10.1186/s13195-021-00870-z.
Cognitive reserve is most commonly measured using socio-behavioural proxy variables. These variables are easy to collect, have a straightforward interpretation, and are widely associated with reduced risk of dementia and cognitive decline in epidemiological studies. However, the specific proxies vary across studies and have rarely been assessed in complete models of cognitive reserve (i.e. alongside both a measure of cognitive outcome and a measure of brain structure). Complete models can test independent associations between proxies and cognitive function in addition to the moderation effect of proxies on the brain-cognition relationship. Consequently, there is insufficient empirical evidence guiding the choice of proxy measures of cognitive reserve and poor comparability across studies.
In a cross-sectional study, we assessed the validity of 5 common proxies (education, occupational complexity, verbal intelligence, leisure activities, and exercise) and all possible combinations of these proxies in 2 separate community-dwelling older adult cohorts: The Irish Longitudinal Study on Ageing (TILDA; N = 313, mean age = 68.9 years, range = 54-88) and the Cognitive Reserve/Reference Ability Neural Network Study (CR/RANN; N = 234, mean age = 64.49 years, range = 50-80). Fifteen models were created with 3 brain structure variables (grey matter volume, hippocampal volume, and mean cortical thickness) and 5 cognitive variables (verbal fluency, processing speed, executive function, episodic memory, and global cognition).
No moderation effects were observed. There were robust positive associations with cognitive function, independent of brain structure, for 2 individual proxies (verbal intelligence and education) and 16 composites (i.e. combinations of proxies). Verbal intelligence was statistically significant in all models. Education was significant only in models with executive function as the cognitive outcome variable. Three robust composites were observed in more than two-thirds of brain-cognition models: the composites of (1) occupational complexity and verbal intelligence, (2) education and verbal intelligence, and (3) education, occupational complexity, and verbal intelligence. However, no composite had larger average effects nor was more robust than verbal intelligence alone.
These results support the use of verbal intelligence as a proxy measure of CR in cross-sectional studies of cognitively healthy older adults.
认知储备最常使用社会行为学代理变量来衡量。这些变量易于收集，解释简单，并且在流行病学研究中与痴呆和认知能力下降的风险降低广泛相关。然而，在认知储备的完整模型中，具体的代理变量因研究而异，并且很少被评估（即与认知结果测量和大脑结构测量一起）。完整模型可以测试代理变量与认知功能之间的独立关联，以及代理变量对大脑认知关系的调节作用。因此，指导认知储备代理测量选择的经验证据不足，并且各研究之间的可比性较差。
在一项横断面研究中，我们评估了 5 种常见代理变量（教育、职业复杂性、言语智力、休闲活动和运动）以及这些代理变量的所有可能组合在 2 个独立的社区居住的老年成人队列中的有效性：爱尔兰老龄化纵向研究（TILDA；N=313，平均年龄 68.9 岁，范围 54-88）和认知储备/参考能力神经网络研究（CR/RANN；N=234，平均年龄 64.49 岁，范围 50-80）。使用 15 个模型，这些模型包括 3 个大脑结构变量（灰质体积、海马体体积和平均皮质厚度）和 5 个认知变量（词汇流畅性、加工速度、执行功能、情景记忆和整体认知）。
未观察到调节效应。有 2 个个体代理变量（言语智力和教育）和 16 个组合（即代理变量的组合）与认知功能呈稳健的正相关，与大脑结构无关。言语智力在所有模型中均具有统计学意义。教育仅在以执行功能为认知结果变量的模型中具有统计学意义。在超过三分之二的大脑认知模型中观察到 3 个稳健的组合：（1）职业复杂性和言语智力的组合，（2）教育和言语智力的组合，以及（3）教育、职业复杂性和言语智力的组合。然而，没有一个组合的平均效应更大，也没有一个组合比言语智力本身更稳健。
这些结果支持在认知健康的老年成年人的横断面研究中使用言语智力作为认知储备的代理测量。
