Purpose of the article
Cognitive training for Attention Deficit/Hyperactivity Disorder (ADHD) has shown promising, although mixed results. In post-hoc analyses, we evaluate effects of cognitive training using a novel composite cognition score as the outcome for children attending at least 16 sessions of training, dose-response of training and associations between symptoms and cognitive functioning.

Materials and methods
Children (age 6–13) with ADHD were randomized to intervention (n = 26) or control (n = 34). For the current analysis, we restricted the intervention group to children, who completed at least 16 sessions of cognitive training (n = 26) and examined a dose response within that group.

Results
Cognition improved significantly in the intervention, but not control group. Amount of the completed training sessions correlated significantly with the amount of cognitive improvement.

Conclusion
Variations in dose and frequency of training may be an important source of the variance in previous studies.