Anxiety can be a symptom of
bipolar disorder. This was recognized by the fellow who originally described
bipolar disorder as such, Dr. Emil Kraepelin, back in 1921. He described "anxious mania", and also "excited depression", which included a "great restlessness". He specifically named anxiety as one of the components of this illness. All that requires saying, because "anxiety" is not generally regarded as a bipolar symptom.