How Much Does A Private ADHD Diagnosis Cost? You may need to go the private option if you are an adult who suffers from ADHD. This is a viable option since private psychiatrists have a lot of experience in diagnosing people with ADHD. They will also check them for co-morbidities http://www.stes.tyc.edu.tw/xoops/modules/profile/userinfo.php?uid=1373103