Around 5% of NZ children have Attention deficit/hyperactivity disorder (ADHD). ADHD is strongly linked with cognitive deficits, making the children at risk for lower educational and employment attainment later in life. Improving our ability to detect and trace ADHD-related cognitive deficits will enable early intervention and evaluation of treatment progress. Yet, our NZ population alone is too small to allow for optimal methods to identify key brain processes underlying ADHD. Fortunately, ‘big data’ including very large numbers of detailed brain images available through our collaborators in the US, and novel machine-learning that enables analysis of big data are a specialty of our research program. Combined with an expert in ADHD, brain imaging experts, ready access to the big data, and a recent pilot approach that has proven successful, the proposed study provides an optimal opportunity to identify the key brain processes underlying ADHD at the earliest developmental stage possible.