"The idea of evidence-based medicine is difficult within mental health as a whole, although it's of course an aim that we should have," he says. "At the same time, we know that diagnoses in psychiatry are just a classification system. Even though you give a person a diagnosis of schizophrenia, you do not see any malfunction in the brain besides what you experience by engaging in a conversation with the person. You cannot see anything on the CT or the MRI images."
https://www.bbc.co.uk/news/stories-56097028
