CONCLUSIONS: Learning difficulties co-occurred more frequently with each other (homotypic) than with ADHD (heterotypic co-occurrence). Both ADHD symptoms and learning difficulties showed trait-like stability. After accounting for these, ADHD symptoms were no longer linked to reading fluency or arithmetic. However, more ADHD symptoms predicted later declines in reading comprehension, likely because comprehension requires sustained attention – often impaired in children with hyperactivity and…
