Jim, I found a reference on Medline as follows: Schneider F, Gur RC, Jaggi JL, Gur RE. Differential effects of mood on cortical cerebral blood flow: a 133xenon clearance study. Psyciatry Res 1994 May; 52(2):215-36. The authors are located at Univ. Pennsylvania Dept. Psyciatry. Do you know them? From their article, I had the impression that the regional cerebral blood flow of an ADHD is somewhat similar to the happy mood. Another reference supports this somewhat: George MS et al, Brain activity during transient sadness and happiness in health women. Am. J. Psychiatry 1995 Mar;152(3):341-5.