The quick answer is yes, but the reality is that this is an area of ongoing confusion and some controversy. Up until recent years, it was thought that younger children were somehow immune to major psychiatric disorders such as major depressive disorder, bipolar disorder, and schizophrenia. Part of the confusion has to do with the developing human brain; using adult criteria for children doesn’t work well. Current thinking is that indeed younger children do develop these disorders, but that the symptoms look different from the adult forms.
Bipolar disorder in children may not manifest with the sustained disturbances of mood seen in adults. Rather they may develop rapid and extreme mood swings, often characterized by frequent tantrums and intense irritability and agitation. These episodes may last for days, or several switches from one extreme mood state to another can occur over the course of a few hours.
In dealing with children who may have bipolar disorder, it’s important that medical professionals tease out other behavioral conditions and diagnoses, such as attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD) and various forms of autism and Asperger’s disorder.