Dopamine is a key chemical messenger that does not work efficiently in the ADHD brain. Dopamine helps control the brain’s reward centre. It is essential for sustaining attention, remembering things, and staying motivated because it helps kids interpret information about the importance, relevance, and value of a task and predicts how rewarding the task will be. Thus, dopamine helps kids figure out whether something is going to be fun or not (i.e., worth their while) and ultimately determines their behaviour, such as whether they will get started on something they have been asked to do. If dopamine is running high, such as when an activity is fun or interesting or there are immediate rewards involved, it is much easier for kids to get started on a task than when it is boring or rewards are delayed.
Dopamine affects four key areas of the brain:
Controls executive functions (EF; the CEO of the brain), which are important for controlling behaviour. Learning from mistakes, thinking about the consequences of our actions, making good decisions, suppressing impulses, and paying attention are all part of EF and all the things people with ADHD have trouble with. These difficulties also makes it hard for kids with ADHD to finish tasks because of the amount of effort it takes to get started, to focus, to sustain motivation, to avoid distraction, and to remember what steps to do in what order; even for daily routine tasks.
Important for memory, as well as regulating attention and emotions. Many kids with ADHD have trouble with arousal, or maintaining alertness (especially to boring things), which involves this part of the brain. This part of the brain also reinforces behaviours (usually the silly ones).
The amygdala and hippocampus are important parts of the limbic system that are affected by ADHD. The amygdala helps kids to process and manage emotions. Kids with ADHD feel emotions quite intensely and cannot cope well with their emotions, resulting in overboard emotional reactions to things.
The hippocampus is related to long-term memory but is also important for learning, motivation, and emotions. Like the amygdala, it plays a role in stopping automatic (emotional) reactions and leads to problems with hyperactivity.
A group of structures in the brain that are important for voluntary movement, learning, emotion, and thinking. In the ADHD brain, these structures disrupt communication between different parts of the brain, which makes it hard to avoid automatic responses to things. As a result, kids with ADHD tend to engage in inattentive and impulsive behaviours.
Reticular activating system
Includes several neural circuits connecting different parts of the brain among the many pathways that enter and leave the brain. It is responsible for the sleep-wake cycle and regulating arousal. Low neurotransmitter activity here makes it hard for kids to filter out important information from irrelevant/distracting background noise and also leads to inattentive, impulsive, and/or hyperactive behaviours.
Read more about the ADHD brain.