Retrospective and prospective time deficits in childhood ADHD: The effects of task modality, duration, and symptom dimensions.

Time estimation is believed to be an adaptive function in human life. In the present study, prospective and retrospective time estimation are studied in both clinical-referred school-aged children with ADHD-C and healthy community control children, while examining more specifically the effects of type of time estimation task, length of time intervals (i.e., ranging from 3-90 s), and continuous scaling of the main ADHD symptom clusters (i.e., inattention vs. hyperactivity/impulsiveness). On a prospective verbal time estimation test, children with ADHD-C showed significant more overestimation compared to controls. For the majority of short-to-medium time intervals, this overestimation was predicted only by the continuous levels of impulsiveness or a disturbed self-regulation, indicating a dysregulation of the internal clock in ADHD. The same holds for the retrospective time estimation task. In contrast, an ADHD-related underestimation on the prospective time reproduction task was found for the longer intervals. In contrast to verbal time estimation, levels of inattention, and not the levels of impulsiveness, predicted underestimation on the time reproduction task. Our results point thereby towards parallel networks for regulating attention/working memory versus impulse regulation/inhibition as potential loci for dysfunction. These results are in contrast to the frequently cited global inhibitory executive function deficit hypothesis.