Although ADHD symptoms and the disturbances they cause to daily living are reported to persist from childhood to adulthood, recent cohort studies have raised questions regarding the continuity of ADHD from childhood to young adulthood. This article aims to review the results of large-scale cohort studies and to address predictive factors associated with persistence into adulthood. Prospective observational studies of non-ADHD children suggested that "late-onset" ADHD results from obsessive-compulsive or anxiety disorders in females and substance-related disorders in males. Therefore, it is important to differentiate psychiatric disorders from ADHD symptoms.
 Predictive factors associated with persistence into adulthood have also been examined. Neuropsychological and neuroimaging studies revealed deficits in executive functions, delay aversion, and timing among adults and children with ADHD. However, it has also been reported that cerebellar volume, poor connectivity in the inferior front-occipital and uncinate fasciculi, and lower activation in both inferior frontal gyri are associated with functional outcomes in adulthood. On the other hand, the severity of ADHD symptoms, history of ADHD treatment, and comorbidity of conduct and depressive disorders are also associated with persistence into adulthood. These results suggest that persistence in adulthood is related to neurobiological backgrounds, and children with ADHD who require medical intervention or who have behavioral problems will exhibit persistence into adulthood.
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