You’ve been part of our ABCD study for four years now, and we want to thank you for working with us. Four years is a long time. This token of appreciation is a small way for us to tell you how important your participation has been.

You should know that you are part of a very special group! You are taking part in the world’s largest study of brain development and behavior from childhood into adulthood. The information you have provided is already being used by scientists from all over the United States, and even from other parts of the world. And in the long run, the study is likely to be a major force in improving the health of all youth.

But please remember, even with so much use, your answers are totally confidential, even from your parents. Individual answers are only identified by a participant number, nothing else. We promise to do everything that we can to ensure that the information you provide can never be traced back to you.

We appreciate your continuing to take part in ABCD and look forward to our work with you in the years to come. If you have comments about any of the procedures that you like or that you don’t like, please let your ABCD team know. We will always pass that information along. This is the kind of feedback that allows us to improve the study and keep it interesting for you.

Thanks from your ABCD team!