[Bipolar disorder in children and adolescents: a difficult diagnosis]

Bipolar disorder (BD) is a severe mental condition with neurodevelopmental features that clinically results in pathological fluctuations of mood. Whereas it was classically or traditionally considered as an adult-onset disorder, recent findings suggest that BD may occur very early in the life course, thus, determining what is now called Juvenile bipolar disorder (JBD). One of the reasons for which JBD has been so difficult to identify is that JBD primary symptoms vary much from the typical adulthood BD clinical expression. Euphoric mood is rare in JBD, while irritability mood, aggressive temper, mixed manic state onset, rapid cycling, anger outbursts and chronic course of symptoms are much more frequent. This specific clinical presentation makes JBD difficult to differentiate from other diagnoses related to pathological externalizing behaviours, including conduct disorder, oppositional provocative disorder, and attention deficit-hyperactivity disorder.