Neural mechanisms of childhood-onset bipolar illness.

Abstract

Substantial evidence exists for a cohort effect (earlier onset and increased prevalence) for both unipolar and bipolar affective disorder in every generation born since World War II. This effect could be related to inherited mechanisms (e.g., bi-Hneal pedigrees or genetic anticipation) or to environmental/experiential effects on gene expression (e.g., stressor effects on the induction of transcription and growth factors, enzymes, hormones and their receptors, and signal transduction molecules) as documented in preclinical models of neonatal maternal separation. This laboratory evidence is summarized and new clinical data on the impact of severe stressors on the unfolding course of bipolar illness are noted. The reported occurrence of childhood or adolescent physical or sexual abuse, compared to those who report their absence, is associated with: earlier bipolar illness onset; faster cycling (including ultradian) patterns; increased Axis I and II comorbidities; and increased time ill in a prospective year of follow-up. Selectively, physical abuse was associated with a reported pattern of increasingly severe mania and sexual abuse with increased numbers of serious suicide attempts. In a retrospective survey of parents of children with an approximate average age of 13 who were diagnosed with bipolar illness (compared to those with other diagnoses and those with no diagnosis), a cluster of symptoms related to irritability and dyscontrol differentiated the bipolar children earliest. These symptoms included: temper tantrums, irritability, inattention, hyperactivity, impulsivity, poor frustration tolerance, and increased aggression. Given the growing evidence that episodes of affective dysfunction can not only convey morbidity and mortality, but may also sensitize to further recurrence and thus change the course of illness, opportunities abound for early recognition and intervention in childhood onset bipolar illness. Such a successful endeavor would both allow a more normal psychobiological development and allow the possibility of preventing the unfolding of more full-blown bipolar illness altogether.