Defining the bipolar spectrum and treating bipolar II disorder.

The treatment of bipolar II disorder may be complicated by the lack of a universal definition of the bipolar spectrum and by the limited number of studies focusing on bipolar II disorder pharmacotherapy. The appropriate first-line treatment for bipolar II disorder is still being studied, but according to the limited research, antidepressants, mood stabilizers, anticonvulsants, and atypical antipsychotics have been safe and effective in the acute and maintenance treatment of bipolar II depression and/or hypomania or mania. A consensus should be reached on the definition of the bipolar spectrum, and further research is needed to determine the best first-line treatment for bipolar II disorder.