Bipolar Disorder is a severe mental disorder characterized by mood instability which results in periods of mania and depression, which can last days to weeks and be of varying severity, as well as chronic symptoms including but not limited to emotional dysregulation and disturbances in circadian rhythm. Including all major subtypes of Bipolar Disorder, 4.4% of the population is affected by this disease (Leboyer et. al, 2010). Currently, the understanding of Bipolar Disorder is that it is a disease with multiple causative factors, none of which are fully understood. However, significant findings have pointed towards a number of potential molecular targets, mainly proteins related to serotonin and melatonin biosynthesis (neurotransmitters that play a role in mood regulation and regulation of circadian rhythm, respectively) (Kripke, et. al. 2011, Etain, et. al. 2012), as well as proteins like GSK-3 which have been found to be affected by common treatments of Bipolar Disorder, in this case lithium (Can, et. al. 2014, Freland and Beaulieu, 2012).
This focus on current treatment methods highlights the difficulties of studying mental disorders, as most of the current research that is suggesting biochemical reasoning for the disease state has been arrived at not by studying the disease directly but rather by looking for the targets of the treatments, most of which were discovered only after the treatments went into use. The number of different treatments used is significant and varied, ranging from mood stabilizers like lithium and valproic acid, to atypical anti-psychotics (resperidone, etc.) and antidepressants (sertraline, paroxetine, etc.) (from the NIMH, The National Institute of Mental Health). These treatments were, for the most part, developed and used prior to any biochemical mechanisms for their action being proven (Ginsberg et. al. 2012), as such the research community is now working backwards by studying the current treatment methods and determining what sorts of interactions they have in the body, and using these findings to figure out what sorts of molecules and proteins are involved in the disease state of Bipolar Disorder.