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 continued to meet criteria for the disorder (Halperin et al., 2008). More recently, we showed a related link between higher-order neurocognitive development and symptom remission in preschoolers with ADHD (Rajendran, Trampush, Rindskopf, Marks, O’Neill & Halperin, 2013). Adaptations in working memory may thus underlie some of the symptom heterogeneity in ADHD over time, and may be a viable endophenotype that is sensitive to both dopamine receptor function and developmental factors. It has been hypothesized that developmental changes in dopaminergic networks in the prefrontal cortex may play a central role in the trajectory of ADHD, but have a minimal role in the initial onset of symptoms (Halperin & Schulz, 2006).
