Randomization
WM anomaly
A secure, computer-generated clinical research platform was used for participant randomization with a 1:1 allocation ratio. At the end of the initial visit, each child was randomly allocated to either the intervention or control group. This platform used a permuted block design stratified on the center and gemellarity: singleton or twin (ie, if 1 twin had a WM anomaly, only this child was selected for randomization; if both twins had a diminished WM, both were randomized to the same group to reduce contamination). Children randomized to the intervention group received cognitive training.