Latent profile analysis of working memory performance in a sample of children with ADHD.

The current study used latent profile analysis (LPA) to ascertain distinct groups of children with ADHD (N = 701) in terms of performance on working memory (WM) tasks that tapped visuospatial sketchpad, spatial central executive, and verbal central executive functions. It compared the WM performances of these classes with a clinical comparison group (N = 59). The participants' age ranged from 7 to 16 years (586 males, 71 females). The results of the LPA supported three classes. For all three WM tasks, class 1 (N = 196) had more difficulties than classes 2 (N = 394) and 3 (N = 111), and the clinical comparison group. Class 2 had more difficulties than class 3 and the clinical comparison group, and there was no difference between class 3 and the clinical comparison group. Class 1 had lower IQ and academic abilities, and relatively more individuals with depressive disorders. The implications of the findings for understanding ADHD and its treatment are discussed.