Brief report: Evaluation of working memory deficits in children with ADHD using the NIH list sorting working memory task

Variability in working memory (WM) task selection likely contributes to heterogeneity in effect size estimates of deficiencies in youth with attention-deficit/hyperactivity disorder (ADHD). This has resulted in the development of brief, easy to administer assessments such as the NIH List Sorting Working Memory (LSWM) task from the NIH Cognitive Toolbox in hopes of standardizing measurement of this construct. Unfortunately, substantial questions persist regarding the specific constructs being evaluated by this task (e.g., visuospatial [VS] or phonological [PH] WM) as well as the ability of this task to detect WM deficits in previously identified impaired groups (e.g., ADHD). The current study examines the extent to which the LSWM task is associated with VS and PHWM performance as well as symptoms of ADHD. Additionally, we examined the magnitude of differences between ADHD and Typically Developing (TD) youth on this task relative to empirically derived WM tasks utilized in the past. Forty-six children (25 ADHD, 21 TD) completed multiple WM tasks. The LSWM task was moderately associated with PHWM and demonstrated relatively weaker associations with VSWM. Symptoms of inattention and hyperactivity/impulsivity were unrelated to the LSWM task; whereas tasks assessing PH and VSWM were moderately associated with inattention and weakly associated with hyperactivity (VSWM only). No significant between-group differences in performance emerged on the LSWM task; however, significant large-magnitude group differences were observed on both the PH and VSWM tasks. These findings suggest that the LSWM task may lack the ability to detect WM difficulties in youth with ADHD.