Although our model suggests euthymia is a state of normalised dopamine, based on a study demonstrating no significant alteration in the dopamine release paradigm in euthymic patients compared to controls,50 this is not consistent with the finding of elevated DAT in a euthymic state.47 It also remains unclear whether the dopamine hypothesis can completely explain bipolar depression and how dopaminergic dysregulation will be linked to the involvement of other neurotransmitter systems. This evidence concerns the gene SLC6A3 and bipolar disorder.