The Special Case of Bipolar Disorder

Abstract

Bipolar disorder (BD) is one of the most difficult psychiatric disorders to investigate given the wide variation in symptoms, the similarity of these symptoms to those seen in other psychiatric disorders and the problems induced by cycling of mood states between the extremes of mania and depression. These cycles can occur over short time periods or they can even take several years to come about. One of the most confusing factors is that patients with bipolar disease often present first with symptoms that are indistinguishable from depression. Taken together, these factors make identification of individuals with this disorder difficult and, as such, diagnosis can often be delayed or even wrong. This also makes it difficult to treat patients since incorrect or delayed therapy could make these patients worse or even precipitate violent mood swings, or cause a shift in mood state or the development of other medical complications due to medication side effects. There have now been a number of biomarker-based investigations which have been carried out in attempts to increase our knowledge of this disease to help tackle the complications of diagnosis and shed new light on potential newer and better treatments. This chapter reviews the behavioural characteristics of bipolar disorder, followed by outlining what the biomarker studies have told us about what is going on at the level of the pathophysiology. Again, this appears to involve peripheral systems such as alterations in insulin signalling and perturbed inflammatory pathways. Finally, the potential areas for novel and improved treatment approaches are outlined which have been guided by these investigations.