Brain Research, ADHD and Developmental Delays
More recently, a 2007 study commissioned by NIMH provides some hope to parents who may be concerned about their child’s prospects in the future. The study confirmed there are differences between the brains of ADHD children and those of non-ADHD children. However, the study concluded that brain development of children with ADHD follows a normal developmental pattern, but that growth is roughly three years behind that of children without the disorder.
“Finding a normal pattern of cortex maturation, albeit delayed, in children with ADHD should be reassuring to families and could help to explain why many youth eventually seem to grow out of the disorder," said Philip Shaw, M.D., who led the research team . According to the research, approximately half the cortex sites monitored in ADHD children reached their peak thickness at an average age of 10.5. Meanwhile, other children saw their cortex sites reach that level of thickness by 7.5 years of age.
The cortex is important because it is the region of the brain responsible for controlling thinking, attention and planning. A February 2011 editorial in The American Journal of Psychiatry referenced studies indicating a thinning of the cortex is related to an increase in the severity of ADHD behaviors.
A 2010 study published in Molecular Psychiatry also supports earlier brain research that ADHD is a physical problem instead of an emotional or behavioral one. In this study, PET scans of adults diagnosed with ADHD revealed decreased function in the brain’s dopamine reward pathways. Essentially, those with ADHD don’t get the same boost of feel-good dopamine as those with normal brain functions. Researchers hypothesize the reduced level of dopamine explains why those with ADHD often appear to lack motivation and have difficulty staying on task for extended periods of time.