Background: Psychiatric illnesses like bipolar disorder are increasingly understood to be neurodevelopmental disorders with clinical, psychological, and biological indicators recognizable long before the emergence of the full-blown syndromes.
Methods: This paper is a selective review of findings from studies of high-risk children of affected parents that inform the knowledge of illness risk and development markers of bipolar disorder. We specifically focus on candidate clinical, biological, and psychological risk indicators that could serve as targets for future early intervention and prevention studies.
Results: There is convergent evidence from prospective studies that bipolar disorder typically debuts as depressive episodes after puberty. In some high-risk children, sleep and anxiety disorders precede mood disorders by several years and reflect an increased vulnerability. An association between early exposure to adversity (eg, exposure to parental illness, neglect from mother) and increased risk of psychopathology may be mediated through increased stress reactivity evident at both behavioral and biological levels. Inter-related psychological processes including reward sensitivity, unstable self-esteem, rumination, and positive self-appraisal are risk factors for mood disorders. Disturbances in circadian rhythm and immune dysfunction are associated with mood disorders and may be vulnerability markers influenced by these other risk factors.
Conclusions: There is accruing evidence of a number of measurable and potentially modifiable markers of vulnerability and developing illness in youth at familial risk for bipolar disorder. Longitudinal studies of multiple biological and psychological risk processes in high-risk offspring, both individually and together, will improve our understanding of illness onset and lead to the development of specific early interventions.