Mental illness caused by a brain aneurysm

In another post, i mentioned a connection between mental illnesses and brain aneurysms  .. i have both conditions.

I believe my aneurysm happened in 1996.  That night i had the worst ever head pain at about 2am.  At the time, the only thing that could treat it was hydrocodone,  a strong opiate painkiller.   It was less than 2 mos. Later i had my first exposure to mental illness and its treatment.,to%20schizophrenia%20or%20bipolar%20disorder.

The above link says unruptured brain aneurysms bring symptoms similar to bipolar disorder and schizophrenia, both of which I’ve been diagnosed with.  Of course, now the question is… if there are physical causes, why call it a mental illness.