They are not brain diseases. The psychological stresses etc., come first and these lead to structural changes in the brain. Also these changes are reversible through psychological means (brain plasticity). Also, physical health conditions that you have listed have observable pathology and cellular mechanisms that can be understood. This is not at all the case for mental conditions - despite decades of research, scientists have not been able to find any structural or other brain differences between people with and without mental health issues.  This is the reason that there are no objective tests to diagnose these mental conditions - there are no blood tests, tissue tests, X-rays or any of that. Diagnosis made this way also fails to meet the Virchowian standard of disease.