The early course of bipolar disorder in youth at familial risk.

INTRODUCTION: There has been substantial clinical and research interest in describing the complete natural history of bipolar disorder, and related to this significant debate in regard to the validity of the bipolar diagnosis in very young children. Given the high heritability of bipolar disorder, longitudinal high risk studies can provide important information in regard to the evolution of the disorder.
METHODS: A selected review and discussion of the findings from key longitudinal high risk studies are presented focusing on the relevance for mapping the early course of illness, addressing the validity of the bipolar diagnosis in very young referred children and implications for diagnosis and organization of services.
RESULTS: To date, there have been findings reported from several longitudinal high risks studies starting with well characterized affected parents, all of which support an evolution of psychopathology from non-specific disorders to frank bipolarity. Early childhood antecedents include internalizing and sleep disorders and typically not behavioural disorders. In the majority of cases, the early mood pathology and associated morbidity is related to the depressive polarity. None of these studies have reported a single case of pre-pubertal mania.
CONCLUSIONS: These findings highlight the importance of considering the clinical course and the family history in diagnostic formulation in pediatric patients early in the course of a psychiatric illness. The implications of these findings for early intervention and organization of child psychiatry services are discussed.