How Much Does A Private ADHD Diagnosis Cost? You might need to take the private option if you are an adult who suffers from ADHD. This is a good option because private psychiatrists are more experienced in diagnosing adults suffering from ADHD. They also test them for co-morbidities like depression https://telegra.ph/The-10-Scariest-Things-About-Private-ADHD-Assessment-Wales-03-07