Earliest symptoms discriminating juvenile-onset bipolar illness from ADHD

Controversy surrounds the diagnosis and earliest symptoms of childhood-onset bipolar illness, emphasizing the importance of prospective longitudinal studies. To acquire a preliminary, more immediate view of symptom evolution, we examined the course of individual symptoms over the first 10 years of life in juvenile-onset bipolar illness (JO-BP) compared with attention-deficit hyperactivity disorder (ADHD). Parents of formally diagnosed children retrospectively rated 37 symptoms in each year of the child's life based on the degree of dysfunction in their child's usual family, social, or educational roles. A subset of children with onset of bipolar disorder prior to age 9 (JO-BP) compared with those with ADHD was the focus of this analysis. Brief and extended periods of mood elevation and decreased sleep were strong early differentiators of JO-BP and ADHD children. Depressive and somatic symptoms were later differentiators. Irritability and poor frustration tolerance differentiated the two groups only in their greater incidence and severity in JO-BP compared with a moderate occurrence in ADHD. In contrast, hyperactivity, impulsivity, and decreased attention showed highly similar trajectories in the two groups. Elevated mood and decreased sleep discriminated JO-BP and ADHD as early as age 3, while classic ADHD symptoms were parallel in the groups. These retrospective results provide preliminary insights into symptom differences and their temporal evolution between bipolar disorder and ADHD in the first 10 years of life.