Aging
Sex differences in cognitive predictors of functional independence in an oldest-old cohort: A multi-group structural equation modeling approach Natalie Pandher* Natalie Pandher Pandher Pandher Pandher Pandher Pandher Pandher University of California, Davis
Independent living, a critical aspect of healthy aging, can be measured by Instrumental Activities of Daily Living (IADLs). IADL impairments are prevalent in older adults, women, and individuals with dementia/MCI, but sex differences in cognition-IADL pathways are unclear. We assessed if sex moderates associations of cognitive function with functional independence in the oldest-old from cross-sectional data on IADLs and cognition collected in wave 2 of the LifeAfter90 Study. Using confirmatory factor analysis, IADLs of money management, meal preparation, and chores were weighted by factor loadings to create a functional independence latent factor (higher scores = less independence). Z-scored semantic memory (SM), working memory (WM), verbal episodic memory (VEM), and executive function (EF) were measured with the Spanish and English Neuropsychological Assessments Scale. After testing for scalar measurement invariance to account for baseline sex differences in the sample, we employed multi-group structural equation modeling with a weighted least squares estimator and created regression models of cognition and functional independence for each sex while adjusting for age, education, race/ethnicity, and marital status (Fig 1). Sex differences were assessed by the Wald test. The sample (N=475; 62% female) had mean age of 93 (SD= 2.2; range: 90-103 yrs) with 75% college educated, 28% married/partnered, and a race/ethnicity breakdown of 30% White, 26% Black, 21% Asian, 15% Latino/Hispanic, and 8% other. The model revealed sex differences in associations of VEM (βdiff= 0.23; 95%CI: 0.02, 0.44) and EF (βdiff= -0.36; 95%CI: -0.70, -0.02) with functional independence. WM was predictive of functional independence in females only. Our findings suggest memory may play a larger role in independence for females, while executive control is more critical in males. Thus, tailoring independent living support systems to be sex-specific may help promote aging-in-place in the oldest-old.
