Differential Sensitivity of Intraindividual Variability Dispersion and Global Cognition in the Prediction of Functional Outcomes and Premature Mortality in Precariously Housed and Homeless Adults

Precariously housed and homeless individuals are exposed to adverse factors negatively impacting neurocognitive functioning. Intraindividual variability (IIV) across neuropsychological tests (i.e., IIV dispersion) has been used as a marker of frontal system pathology. Increased IIV dispersion has been associated with worse cognitive functioning, everyday functioning, and mortality in a range of older adult and clinical populations. The current study was the first to examine IIV dispersion as a predictor of functioning and mortality in persons who are homeless or precariously housed. Participants were 407 community-dwelling adults, followed for up to 12 years. Neurocognition was assessed at baseline and IIV dispersion was derived using a battery of standardized tests. Functional outcomes (social, physical) were obtained at baseline and last follow-up. Mortality was confirmed with coroner’s reports and hospital records (N = 103 deaths). Linear regressions were used to predict current and long-term social and physical functioning from IIV dispersion. Cox regression models were used to examine the relation between IIV dispersion and mortality. Covariates included global cognition, age, and education. Greater IIV dispersion predicted worse current physical functioning (B = -0.37 p = .021), while greater global cognition predicted better current (B = 0.22, p = .012) and long-term social functioning (B = 0.42, p < .001). Global cognition, but not IIV dispersion, predicted mortality in individuals less than 55 years old (HR = 0.50, p = .013). IIV dispersion may be a unique marker of emergent physical health dysfunction in precariously housed adults and may be best used in conjunction with traditional neuropsychological indices.