DesRuisseaux Libby A, Guevara Jasmin E, Duff Kevin
Department of Psychology, University of Utah, Salt Lake City, UT 84112, USA.
Department of Neurology, Layton Aging and Alzheimer's Disease Center, Oregon Health & Science University, Portland, OR 97239, USA.
Arch Clin Neuropsychol. 2025 Jan 21;40(1):1-12. doi: 10.1093/arclin/acae054.
Dispersion is a form of intra-individual variability across neuropsychological tests that has been shown to predict cognitive decline. However, few studies have investigated the stability and predictive utility of both across- and within-domain dispersion. The current study aims to fill these gaps in the literature by examining multiple indices of dispersion in a longitudinal clinical sample of individuals diagnosed with mild cognitive impairment (MCI) at baseline.
Two hundred thirty-eight MCI patients from a cognitive disorders clinic underwent testing at baseline and after approximately 1.5 years. Linear regression was used to examine whether baseline across- and within-domain dispersion predicted cognitive decline in individuals whose diagnostic classification progressed to dementia (i.e., MCI-Decline) and those who retained an MCI diagnosis at follow-up (i.e., MCI-Stable). Cognitive decline was operationalized dichotomously using group status and continuously using standardized regression-based (SRB) z-scores.
Dispersion variables at baseline and follow-up were positively correlated in both groups, with the exception of within-domain executive functioning and language dispersion in the MCI-Decline group. None of the dispersion variables predicted diagnostic conversion to MCI. Using SRB z-scores, greater across-domain dispersion predicted greater overall cognitive decline at follow-up, but this was not the case for within-domain variables with the exception of visuospatial skills.
Results suggest that across- and within-domain dispersion are relatively stable across time, and that across-domain dispersion is predictive of subtle cognitive decline in patients with MCI. However, these results also highlight that findings may differ based on the tests included in dispersion calculations.
离散度是神经心理学测试中个体内部变异性的一种形式，已被证明可预测认知衰退。然而，很少有研究调查跨领域和领域内离散度的稳定性及预测效用。本研究旨在通过检查基线时被诊断为轻度认知障碍（MCI）的个体纵向临床样本中的多个离散度指标，填补文献中的这些空白。
来自认知障碍诊所的238名MCI患者在基线时和大约1.5年后接受了测试。线性回归用于检验基线时的跨领域和领域内离散度是否能预测诊断分类进展为痴呆的个体（即MCI-衰退组）以及随访时仍保持MCI诊断的个体（即MCI-稳定组）的认知衰退。认知衰退通过分组状态进行二分法操作化，并通过基于标准化回归（SRB）的z分数进行连续操作化。
两组在基线和随访时的离散度变量均呈正相关，但MCI-衰退组的领域内执行功能和语言离散度除外。没有一个离散度变量能预测向MCI的诊断转换。使用SRB z分数，更大的跨领域离散度预测随访时总体认知衰退更大，但领域内变量（视觉空间技能除外）并非如此。
结果表明，跨领域和领域内离散度随时间相对稳定，且跨领域离散度可预测MCI患者的细微认知衰退。然而，这些结果也突出表明，根据离散度计算中所包含的测试，结果可能会有所不同。
