Neuropsychological functioning was measured using a single latent variable that encompassed multiple domains for three main reasons. First, ADHD children show deficits across many domains of neuropsychological functioning including memory (Felton, Wood, Brown, Campbell, & Harter, 1987), motor (Blondis, 1999; Steger et al., 2001), language (Purvis & Tannock, 1997; Tirosh & Cohen, 1998), and visuomotor precision (Raggio, 1999). Second, though some research has suggested a variable number of factors of the NEPSY based on age (Mosconi, Nelson, & Hooper, 2008), other research has found that the NEPSY may be best conceptualized as single factor rather than as unique and uncorrelated domains (Stinnett, Oehler-Stinnett, Fuqua, & Palmer, 2002). Finally, neuroimaging data from ADHD children indicate delays throughout much of the neocortex, rather than a specific region (Shaw et al., 2006).
