Klepacz Laura M, Cerino Eric S, Hamm Jeremy M
Department of Psychology, North Dakota State University, Fargo, North Dakota, USA.
Department of Psychological Sciences, Northern Arizona University, Flagstaff, Arizona, USA.
J Gerontol B Psychol Sci Soc Sci. 2025 May 8;80(6). doi: 10.1093/geronb/gbae201.
Although research has shown that higher levels of within-person variability across cognitive tasks (dispersion) are associated with cognitive decline in clinical samples, little is known about dispersion in comparatively younger, nonclinical, and national samples. A better understanding of dispersion is needed to elucidate for whom and under what circumstances dispersion can be used as a reliable indicator of cognitive health.
We used data from the Midlife in the United States Study (MIDUS; n = 2,229; Mage = 56 years, range = 33-83; 56% female) to: (a) characterize dispersion and its cross-sectional correlates in a nonclinical, adult lifespan sample and (b) examine changes in dispersion over time to determine for whom changes in dispersion may reflect better or worse cognitive aging.
Correlations showed higher levels of dispersion were associated with higher levels of mean performance at both waves (rs = 0.28-0.29). Autoregressive main effect models showed that increases in dispersion were associated with less decline in mean performance over the 2-wave, 9-year follow-up period (β = 0.17, p < .001). Moderation models showed that the link between change in dispersion and change in mean performance was pronounced in comparatively older adults (β = 0.28), women (β = 0.27), individuals with less education (β = 0.23), and those with lower income (β = 0.23; all ps < .001).
Findings suggest that increases in dispersion may not always be maladaptive in normative, adult lifespan samples and may reflect healthier cognitive profiles in individuals who are at greater risk for cognitive impairment.
尽管研究表明，临床样本中跨认知任务的个体内变异性（离散度）较高与认知能力下降有关，但对于相对年轻、非临床和全国性样本中的离散度知之甚少。为了阐明离散度可以作为认知健康可靠指标的对象和情况，需要更好地理解离散度。
我们使用了美国中年研究（MIDUS；n = 2229；年龄中位数 = 56岁，范围 = 33 - 83岁；56%为女性）的数据，以：（a）描述非临床成人寿命样本中的离散度及其横断面相关性，以及（b）检查离散度随时间的变化，以确定离散度的变化可能反映认知老化变好或变差的对象。
相关性分析表明，在两个时间点，较高的离散度水平均与较高的平均表现水平相关（r值 = 0.28 - 0.29）。自回归主效应模型显示，在为期9年的两波随访期间，离散度的增加与平均表现下降较少相关（β = 0.17，p <.001）。调节模型显示，在相对年长的成年人（β = 0.28）、女性（β = 0.27）、受教育程度较低的个体（β = 0.23）和收入较低的个体（β = 0.23；所有p值 <.001）中，离散度变化与平均表现变化之间的联系较为显著。
研究结果表明，在正常的成人寿命样本中，离散度的增加可能并不总是具有不良适应性，并且可能反映出认知障碍风险较高个体更健康的认知特征。
