Attention Deficit/Hyperactivity Disorder (ADHD) is a clinical syndrome characterized by an onset in early life. More than 65% of patients persist with manifestations of ADHD in adulthood. These symptoms may interfere in activities of daily-living, interpersonal relationships and professional and academic achievement. Nevertheless, the observation of an important group of adults with ADHD who do not show significant difficulties in the areas mentioned before puts into evidence the prognostic heterogeneity of this disorder. One of the current, most accepted explanations is the Double-Pathway Model: two double-dissociated deficits (Executive Disorders and Delayed-Reward Processing impairments) are involved in the genesis of ADHD, which explains the existence of different behavioral phenotypes. Moreover, personality traits like tenacity or perseverance are associated with higher levels of achievement in adults. On these grounds, we propose the hypothesis that the neurobiological correlate of tenacity/perseverance is a preserved Delayed-Reward Processing capacity, although further studies are needed to verify this idea.