Because mental illnesses do not come in a neat box. I am bipolar but I do not fit in every category of the illness of bipolar disorder. I am an individual case just like everyone who is mentally ill. No two people with mental illnesses are alike, and that goes to say not every two people with the same mental illness are alike.

I take lithium and zyprexa, but I have tried many other medications that treats the same illness, but found that they are not compatible with my brain chemistry. However, other people with bipolar disorder find that some medications work better than others due to their own brain chemistry compatibility.

A family doctor can make a diagnosis in ten minutes because he can assess symptoms. Symptom #1, #2, aha! You must be this. Even the most prestigious psychologist can falter at making a sound diagnosis because he can only assess what is being told and what he can observe. It is truly impossible to make a sound diagnosis because mental illnesses vary in severity and at times calls for multiple diagnoses. There are many factors in diagnosing but in simplicity a mental illness cannot be diagnosed the same as a physical ailment or disorder.