Working Memory and Intraindividual Variability as Neurocognitive Indicators in ADHD: Examining Competing Model Predictions

    Authors

    M. J. Kofler; R. M. Alderson; J. S. Raiker; J. Bolden; D. E. Sarver;M. D. Rapport

    Comments

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    Abbreviated Journal Title

    Neuropsychology

    Keywords

    attention-deficit/hyperactivity disorder; working memory; variability; reaction time; ex-Gaussian; ATTENTION-DEFICIT/HYPERACTIVITY DISORDER; DEFICIT HYPERACTIVITY; DISORDER; REACTION-TIME VARIABILITY; LATENT-VARIABLE APPROACH; SHORT-TERM-MEMORY; BEHAVIORAL-INHIBITION; CHILDREN; INTELLIGENCE; TASKS; BOYS; Psychology, Clinical; Neurosciences; Psychology

    Abstract

    Objective: The current study examined competing predictions of the default mode, cognitive neuroenergetic, and functional working memory models of attention-deficit/hyperactivity disorder (ADHD) regarding the relation between neurocognitive impairments in working memory and intraindividual variability. Method: Twenty-two children with ADHD and 15 typically developing children were assessed on multiple tasks measuring intraindividual reaction time (RT) variability (ex-Gaussian: tau, sigma) and central executive (CE) working memory. Latent factor scores based on multiple, counterbalanced tasks were created for each construct of interest (CE, tau, sigma) to reflect reliable variance associated with each construct and remove task-specific, test-retest, and random error. Results: Bias-corrected, bootstrapped mediation analyses revealed that CE working memory accounted for 88% to 100% of ADHD-related RT variability across models, and between-group differences in RT variability were no longer detectable after accounting for the mediating role of CE working memory. In contrast, RT variability accounted for 10% to 29% of between-group differences in CE working memory, and large magnitude CE working memory deficits remained after accounting for this partial mediation. Statistical comparison of effect size estimates across models suggests directionality of effects, such that the mediation effects of CE working memory on RT variability were significantly greater than the mediation effects of RT variability on CE working memory. Conclusions: The current findings question the role of RT variability as a primary neurocognitive indicator in ADHD and suggest that ADHD-related RT variability may be secondary to underlying deficits in CE working memory.

    Journal Title

    Neuropsychology

    Volume

    28

    Issue/Number

    3

    Publication Date

    1-1-2014

    Document Type

    Article

    Language

    English

    First Page

    459

    Last Page

    471

    WOS Identifier

    WOS:000335334000017

    ISSN

    0894-4105

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