Thank you Ed, for your comments; you often push me to look at things again.
Certainly there are two distinct problems (at least two!); mania and ADHD. Recent suggestions are that a child can have neither, either, or both (Please see my earlier postings on Mania & ADHD comparisons.
Bipolar disorder is seen in prepubertal, pediatric populations(1); likewise, for ADHD. Both disorders are usually chronic. Both appear to be continuous variables rather than discrete disease entities.
ADHD may be relabeled as Behavioral Inhibition Disorder. The new name would reflect consensus that there is a motor problem rather than a sensory one, there is no attention problem in ADHD but rather one of task persistence, and the child fills time by "doing" things rather than by thinking.(2)
I have assumed a continuous distribution of the essential features of subclinical mania into bipolar disorder. Prepubertal mania is thought to be reflected by hyperactivity, talkativeness, impulsiveness, extreme cruelty, and an irritable, labile mood. Faedda's group remarks on the presence of dysphoria, delusions, and high risk of suicide attempts in extreme cases; there are also elevated risks for substance abuse. Cantwell(3) generally endorses this list but appends the feature of high self esteem and, in some adolescents, hypersexuality. He also discussed "mixed mania" in which there are daily shifts in mood from mania to depression combined with a high activity level. Mixed mania shows a poor response to lithium and seems more likely in girls.
The paper by Faedda et al has a historical survey that you will appreciate. Prepubertal mania was recorded in 150 AD, documented often during the Victorian Era and until 1930. The theoreticians then waived it out of existence until the early '70s in this country and the UK.
(1) Faedda G, Baldessarini R, et al. (1995) Pediatric onset of bipolar disorder: A neglected clinical and public health problem. Harvard Rev. of Psychiatry. 3(4), 171-195. Glasser J (1995) Differential diagnosis of ADHD and bipolar disorder. ADHD Report. 3(3), 8-10. Wozniak J, & Biederman J. (1994) Prepubertal mania exists (and coexists with ADHD). ADHD Report, 2(3), 5-6.
(2) Barkley R, (1996) Taking charge of ADHD. NY: Guilford.
(3) Cantwell D. (1995) Treatment of childhood disorders. Albert Einstein Cape Cod Summer Institute. (Dr. Cantwell will again be speaking this summer from August 11-15. See the homepage for information and registration!)