They found that ADHD is largely a developmental problem: the brains of kids with ADHD develop at a significantly slower pace than normal. For instance, the median age by which 50 percent of the cortical points attained peak thickness for the ADHD group was 10.5 years, while the median age for the control group was 7.5 years. This lag was most obvious in the lateral parts of the prefrontal cortex, which is a brain area essential for most of the executive functions that appear to compromised in children with ADHD. (On average, their frontal lobes were three and a half years behind schedule.) The good news, however, is that the ADHD brain almost always recovers from its slow start.
12 June 2009
ADD/ ADHD Study
Here's an important review of and ADD/ADHD study by respected science journalist Jonah Lehrer.