Columbia University.
J Cogn Neurosci. 2024 Sep 1;36(9):2045-2066. doi: 10.1162/jocn_a_02188.
Some theories of aging have linked age-related cognitive decline to a reduction in distinctiveness of neural processing. Observed age-related correlation increases among disparate cognitive tasks have supported the dedifferentiation hypothesis. We previously showed cross-sectional evidence for age-related correlation decreases instead, supporting an alternative disintegration hypothesis. In the current study, we extended our previous research to a longitudinal sample. We tested 135 participants (20-80 years) at two time points-baseline and 5-year follow-up-on a battery of 12 in-scanner tests, each tapping one of four reference abilities. We performed between-tasks correlations within domain (convergent) and between domain (discriminant) at both the behavioral and neural level, calculating a single measure of construct validity (convergent - discriminant). Cross-sectionally, behavioral construct validity was significantly different from chance at each time point, but longitudinal change was not significant. Analysis by median age split revealed that older adults showed higher behavioral validity, driven by higher discriminant validity (lower between-tasks correlations). Participant-level neural validity decreased over time, with convergent validity consistently greater than discriminant validity; this finding was also observed at the cross-sectional level. In addition, a disproportionate decrease in neural validity with age remained significant after controlling for demographic factors. Factors predicting longitudinal changes in global cognition (mean performance across all 12 tasks) included age, change in neural validity, education, and National Adult Reading Test (premorbid intelligence). Change in neural validity partially mediated the effect of age on change in global cognition. Our findings support the theory of age-related disintegration, linking cognitive decline to changes in neural representations over time.
一些衰老理论将与年龄相关的认知能力下降与神经处理的独特性降低联系起来。观察到的与年龄相关的认知任务之间相关性的增加支持了去分化假说。我们之前的研究提供了相反的证据，表明随着年龄的增长，相关性会降低，这支持了另一种解体假说。在目前的研究中，我们将之前的研究扩展到了纵向样本。我们在基线和 5 年随访时测试了 135 名参与者（20-80 岁），使用了一系列 12 种扫描测试，每种测试都涉及四种参考能力之一。我们在行为和神经水平上分别对域内（收敛）和域间（辨别）进行了任务间相关性测试，计算了一个结构有效性的单一度量（收敛-辨别）。在行为层面，横断面的结构有效性在每个时间点都显著不同于随机，但纵向变化不显著。按中位数年龄划分的分析表明，老年参与者表现出更高的行为有效性，这是由更高的辨别有效性（更低的任务间相关性）驱动的。参与者水平的神经有效性随时间而降低，收敛有效性始终大于辨别有效性；这一发现也在横断面水平上得到了观察。此外，在控制了人口统计学因素后，神经有效性随年龄不成比例地下降仍然具有显著性。预测所有 12 项任务平均表现的全局认知（即总体认知）纵向变化的因素包括年龄、神经有效性的变化、教育程度和全国成人阅读测试（即先前的智力水平）。神经有效性的变化部分介导了年龄对总体认知变化的影响。我们的发现支持与年龄相关的解体理论，该理论将认知能力下降与随时间变化的神经表现变化联系起来。
