Psychological Medicine; Cambridge Vol. 48, Iss. 14, (Oct 2018): 2399-2408. Childhood-onset attention-deficit hyperactivity disorder (ADHD) in adults is clinically heterogeneous and commonly presents with different patterns of cognitive deficits. It is unclear if this clinical heterogeneity expresses a dimensional or categorical difference in ADHD.. To read the full article, log in using your MPFT NHS OpenAthens details.