Psychiatric disorers are difficult to diagnose and the field is thus working towards finding new and more quantitative biomarkers. In this study, my colleague Reto Iannaccone used fMRI to classify juvenile ADHD patients with quite promising classification accuracies. He also showed that it is crucial which cognitive process is used for classifying the ADHD subjects.
Iannaccone R, Hauser TU, Ball J, Brandeis D, Walitza S & Brem S (2015).Classifying adolescent attention-deficit/hyperactivity disorder (ADHD) based on functional and structural imaging. Eur Child Adolesc Psychiatry