There is another possibility (just popping out of my head) a person can be Bipolar (different variants) and ADD, my former therapist and pdoc wher Iuse to live said in cases like this they always treat the Bipolar first and then see how it all goes, then will in addition treat the ADD.
Also many decades ago, American pdocs misdiagnosed Bipolar (then called Manic Depression) as Schizophrenia, another setback for the thousands who were not Schizophreic at all, wrong meds also were prescribed, it wasn't till many meetings (conferences) between the US pdocs and European pdocs concluded that Schizophrenia was a "catch all" for disorders that the US didn't quite have the same knowledge that was had in Europe. There are still some "backwards" pdocs that cling to the Schizophrenia DX, and they are wrong in so many cases, this can be due to some of the behaviours both illness share, and the same with ADD. Bipolar disorder is more common than Schizophrenia and easier in the long run to treat, I would get another opinion and also mention the other possiblities. I have a nephew that for years his pdocs insist he is Schizophrenic, and have screwed him up worse with the misdiagnosis, finally a new pdoc hit it on the head, the boy is NOT Schizophrenia, but actually Bipolar with Schizo affective disorder or another variant of Bipolar, geesh, there are so many variations and levels of severity with Bipolar disorder, for example, there is Bipolar-I (which tend to have more manic episodes, some violent) and then there is Bipolar-II, which tends to have more depressive episodes and a few hypomanic tendencies. This one can be rough too, cause the depressive state can be near fatal, many committing Suicide or attempting to as opposed to Bipolar-I
Then there forms of Rapid Cycling, "up and down" with hardly any intervals of no episodes. God, I can talk your ear off, but if you haven't read books yet on this I'd strongly suggest you jump over to the Bipolar forum and see the suggested reading I have at the top line, they are extrememly helpful, and pdoc approved. Other sources of info can be found on the internet, and also at this website, just click on "disorders" up on the top area of the screen. I wish you lots of luck with this, I know how overwhelming this all can be, I was DXed 4 yrs ago as Bipolar-II (mild), ADD (mild) and possible BPD (borderline personality disorder) but the pdoc thinks that could of been from my Bipolar disorder and the way I was not coping with some marital issues, everyone has their own unique stories, the most important thing I tell everyone is to see a pdoc, when things are afffecting your life, and functionabilty.
Feel free to drop by and let us know how things go.

Please take care now

DE

In giving advice seek to help, not please your friend
SOLON