ADHD is a neurological disorder. As a result, someone with the disorder has a slightly different brain compared to someone without ADHD. Exactly how it differs, however, remains something of a mystery, but recent research has shed light on how the brain functions in ADHD patients.
Structure of the ADHD Brain
Maturing at a Different Pace
Using a scanning test called functional magnetic resonance imaging (fMRI), doctors have found that the frontal cortex (an area of the brain responsible for attention, reason, memory, planning, and inhibition) appears thinner and matures slower in children with ADHD (NIMH, 2007).
One study by the National Institute of Mental Health found that in some cases this part of the brain lagged three years behind in age-appropriate development (NIMH, 2007). Eventually, the cortex did catch up and thicken, and this could explain why some children “grow out” of certain symptoms of ADHD, such as impulsive behaviors.
The study also found that the motor cortex (an area of the brain that controls movement) grew much faster than normal in a child with ADHD. This could explain why hyperactive children have a constant need to be moving, even at a young age.
Lower Brain Volume
Researchers have also discovered that, on average, children with ADHD have a lower brain volume and less gray matter than children who do not, especially in regions of the brain responsible for attention and emotion (Castellanos, et al., 2002). This may explain why a person with ADHD struggles to pay attention or control the impulse to lash out.
Function of the ADHD Brain
It’s not just the structure of the brain that differs, but the way the ADHD brain functions as well.
Different areas of the brain communicate by sending signals via neurotransmitters. Dopamine and norepinephrine are neurotransmitters that help send messages between areas of brain associated with attention and motivation. The brain of a person with ADHD may have less of these chemicals available. This is may explain why someone with ADHD has trouble paying attention or performing repetitive tasks.
When people with ADHD are prescribed methylphenidate (a stimulant), it helps increase the amount of dopamine and norepinephrine in the brain. This increase in the level of neurotransmitters seems to improve attentiveness and motivation.