Validity of the NIH toolbox cognitive battery in a healthy oldest-old 85+ sample.

OBJECTIVE: To evaluate the construct validity of the NIH Toolbox Cognitive Battery (NIH TB-CB) in the healthy oldest-old (85+ years old). METHOD: Our sample from the McKnight Brain Aging Registry consists of 179 individuals, 85 to 99 years of age, screened for memory, neurological, and psychiatric disorders. Using previous research methods on a sample of 85 + y/o adults, we conducted confirmatory factor analyses on models of NIH TB-CB and same domain standard neuropsychological measures. We hypothesized the five-factor model (Reading, Vocabulary, Memory, Working Memory, and Executive/Speed) would have the best fit, consistent with younger populations. We assessed confirmatory and discriminant validity. We also evaluated demographic and computer use predictors of NIH TB-CB composite scores. RESULTS: Findings suggest the six-factor model (Vocabulary, Reading, Memory, Working Memory, Executive, and Speed) had a better fit than alternative models. NIH TB-CB tests had good convergent and discriminant validity, though tests in the executive functioning domain had high inter-correlations with other cognitive domains. Computer use was strongly associated with higher NIH TB-CB overall and fluid cognition composite scores. CONCLUSION: The NIH TB-CB is a valid assessment for the oldest-old samples, with relatively weak validity in the domain of executive functioning. Computer use's impact on composite scores could be due to the executive demands of learning to use a tablet. Strong relationships of executive function with other cognitive domains could be due to cognitive dedifferentiation. Overall, the NIH TB-CB could be useful for testing cognition in the oldest-old and the impact of aging on cognition in older populations.

Defining the diagnosis of vascular dementia.

Vascular dementia (VaD) is a heterogeneous term that has evolved to describe the behavioral syndromes associated with a variety of clinical and neuropathologic changes. As such, the VaD literature lacks a clear consensus regarding the neuropsychological and other constituent characteristics associated with various cerebrovascular changes. We address the issues articulated by Paul and colleagues (Paul, Garrett, & Cohen, 2003), by offering four recommendations to refine the clinical assessment and diagnostic decision-making process of individuals with suspected cerebrovascular changes: (a) Describing the nature of vascular changes may facilitate predictions regarding the neuropsychological profile of subtypes of VaD; (b) employ a process approach to assessment, measuring cognitive constructs in addition to test scores to describe the neuropsychological profiles of types of VaD; (c) integrate direct MRI observations of the brain and other collateral data in the diagnostic process; and (d) consider using "vascular cognitive impairment, no dementia" for suspected prodromal VaD.