Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) intraindividual variability in older adults: Associations with disease and mortality.

UNLABELLED: Cognitive intraindividual variability (IIV), or dispersion, has been associated with pathological changes, including cognitive and functional decline. Dispersion is typically assessed with experimental cognitive measures or subtests selected from several batteries, and few studies have examined IIV from a single neuropsychological battery.
METHOD: To address this gap, the current study examined the relationship between the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) IIV, mean cognitive performance, self-reported functioning, and death among 699 individuals between 64 and 94 years of age who were screened for neurological illness and living independently in the community. A coefficient of variation statistic served as the dispersion index and was derived by calculating the within-subject variability of the five RBANS indexes for each participant and dividing this value by the overall test battery mean.
RESULTS: Results revealed that increased dispersion and poorer mean performance simultaneously predicted self-reported memory problems. In addition, participants with elevated dispersion at baseline had increased rates of death nine years later, although this lost significance after controlling for comorbid heart disease. Cluster analysis of the higher dispersion scores revealed four distinct profile patterns that did not differ on the outcome variables.
CONCLUSIONS: Elevated RBANS dispersion is a proxy of co-occurring health problems and may be a useful metric of functional decline and death within community-dwelling geriatric populations.