The adult brain emerges from an organized yet dynamic ‘blueprint’ during the course of development (Andersen, 2003). Higher-order cognitive skills such as working memory are the last to fully develop as maturation of the frontal lobes is more delayed and variable relative to other brain regions (Andersen, 2003; Halperin & Schulz, 2006). Within the prefrontal cortex, developmental improvements in working memory manipulation relative to maintenance are associated with increased recruitment of cells within dorsolateral prefrontal cortex but not ventrolateral prefrontal regions (Crone, Wendelken, Donohue, van Leijenhorst & Bunge, 2006). Moreover, in rats, D1 receptor density is dynamic during development in that it peaks during adolescence and then decreases in adulthood (Andersen, Thompson, Rutstein, Hostetter & Teicher, 2000). DRD1 gene expression also varies in human prefrontal cortex in a similar way across development such that it peaks during late adolescence/early adulthood and then declines during later adulthood (Colantuoni, Lipska, Ye, Hyde, Tao, Leek, Colantuoni, Elkahloun, Herman, Weinberger & Kleinman, 2011). Clinically, we have reported that working memory deficits were only present in adolescents and young adults with childhood-diagnosed ADHD if they
