Is there a clinical prodrome of bipolar disorder? A review of the evidence.

Bipolar disorder is a prevalent, chronic and heterogeneous psychiatric disorder. There is increasing evidence that early recognition and treatment can improve long-term outcomes and prevent disability. Early intervention services for schizophrenia are well-funded and developed throughout the UK with close attention paid to the prodromal or early warning signs of schizophrenia, whereas there are currently no clear guidelines on the clinical, biological and neuropsychological markers of early bipolar disorder. This article reviews the growing literature on the bipolar prodrome and the differentiation between the syndromes of unipolar and bipolar depression.