Within‐Day Variability in Mobile Cognitive Assessments: Associations with Mild Cognitive Impairment and Sociodemographic Factors

Abstract

AbstractBackgroundGreater within‐person variability in cognitive performance on mobile devices is emerging as a sensitive marker of mild cognitive impairment (MCI). It is unclear if sociodemographic differences are associated with this variability, and if so, whether these differences moderate associations between MCI status and within‐person variability. We use a digital health approach with ecological momentary assessments (EMA) to examine sociodemographic differences in within‐day variability among individuals with MCI and those who were cognitively unimpaired (CU).MethodA sample of 308 community‐dwelling older adults from the Einstein Aging Study (mean age = 77.49 years, SD = 4.86, range = 70‐90; 67% female; 45% non‐Hispanic White, 41% non‐Hispanic Black) completed neuropsychological testing and self‐reported questionnaires. Ninety‐eight individuals met Jak/Bondi criteria for MCI. All participants performed mobile tests of processing speed and memory binding on a smartphone up to six times daily over a two‐week period. We employed heterogeneous variance multilevel models to assess sociodemographic and MCI status associations with within‐day variability across assessments. We further tested whether differences in age, gender, race, and education moderated associations between MCI status and within‐day variability.ResultFor processing speed, greater variability was apparent in individuals with MCI, non‐Hispanic Black participants, and individuals with less education (ps<.001). A MCI status*gender interaction occurred; the association between MCI status and variability remained significant for both genders but was smaller among women (p<.01). For memory binding, greater variability was apparent in individuals with MCI, older participants, non‐Hispanic Black participants, and individuals with less education (ps<.001). Numerous interactions occurred; in separate analyses, associations between MCI status and variability remained significant, but were smaller among women, non‐Hispanic Black participants, and individuals with less education (ps<.05).ConclusionIndividuals with MCI exhibited greater within‐day variability in mobile cognitive performance than those who were CU, but the strength of these associations varied by sociodemographic factors. These indices of variability in everyday life may serve as sensitive markers of early cognitive impairment. Future research should examine daily mechanisms and environmental perturbations (e.g., stress, sleep, air pollution) that may explain why associations between MCI status and cognitive variability appeared smaller among women, non‐Hispanic Black participants, and individuals with less education.