How Much Does A Private ADHD Diagnosis Cost? If you are an adult who suffers from ADHD, you may need to go through a private process to be diagnosed. This is a good option as private psychiatrists are more experienced in diagnosing people with ADHD. They also test for co-morbidities http://www.stes.tyc.edu.tw/xoops/modules/profile/userinfo.php?uid=1373132