Connecting Biology to Behavior: Inside the ADHD Brain

The role of dopamine in ADHD behaviors.

Reviewed by Monica Vilhauer Ph.D.

Key points

• ADHD is a neurobiological disorder, and biology influences ADHD behaviors.
• An imbalance in the brain neurochemical dopamine is associated with the symptoms of ADHD.
• Disruptions in certain dopamine pathways lead to attention, memory, and motivation challenges.
• Pharmacological therapies for ADHD increase brain levels of dopamine.

ADHD is the most common neurobiological disorder in children. The key word being neurobiological. When in the throes of raising a neurodivergent child, it’s easy to forget that their behavior is rooted in biology. That's partly because there is no biological test for ADHD, and clinicians need to rely on a patient’s subjective report of their symptoms.

This article is the first in a series on connecting biology to behavior, which aims to help parents, caretakers, and those with ADHD understand the biological basis of ADHD behavior. As my ADHD son likes to say, “My brain made me do it.”

What is dopamine?

ADHD is a neurodevelopmental disorder. The brains of individuals with ADHD develop differently, leading to changes in brain function. A major area of scientific research on ADHD focuses on the role of the brain chemical dopamine. Dopamine is involved in motor control, emotional regulation, reward mechanisms, attention, memory, and other higher cognitive functions. Imaging studies show dopamine-rich areas of the brain are affected in ADHD. In particular, abnormal levels of dopamine in these regions are thought to contribute to ADHD symptoms. In addition, genes for certain dopamine receptors, and enzymes that metabolize dopamine, may be affected in individuals with ADHD.

Dopamine’s action in the brain

Two dopamine pathways implicated in ADHD are the mesocortical and the mesolimbic pathways. Both pathways originate in the dopamine rich ventral tegmental area in the midbrain and project to either the frontal cortex (mesocortical) or the nucleus accumbens (mesolimbic).

Dopamine acting via the mesocortical pathway is involved in the regulation of attention, learning, planning, organizing, memory and controlling your emotions. These are executive functions that enable us to perform appropriate, goal-directed, behaviors. A disruption in the mesocortical dopamine pathway results in executive dysfunction and shows up behaviorally in ADHD kids as distraction, forgetfulness, difficulty completing assignments for school, difficulty following a set of instructions, messy backpacks or rooms, and anger or frustration.

Dopamine acting via the mesolimbic pathway is involved in motivation and reward. Most of us are familiar with the role of dopamine in reward, like the good feeling you get after eating a favorite food. The increase in dopamine release along the mesolimbic pathway results in a pleasurable experience, motivating us to eat the food again. Research suggests decreased functioning of the mesolimbic pathway is related to decreased motivation in adults with ADHD. Thus, individuals with ADHD have an altered response to rewarding stimuli, which potentially underlies the motivational deficits associated with ADHD.

A disruption of the mesolimbic dopamine pathway results in individuals with ADHD to seek stimulating activities that increase dopamine. ADHD brains are motivated by the search for optimal stimulation, which doesn’t involve boring activities like completing homework or cleaning your room, but rather playing fast-paced, action packed video games, texting with friends, spending time on social media, or driving fast. These activities often involve a quick surge of dopamine and immediate reward, which is more desirable to the ADHD brain.

When motivation is lacking, particularly for disliked tasks like homework, creating a dopamine menu — a list of pleasurable and healthy activities that stimulate ADHD brains — may help. For example, when your child’s motivation to finish their math homework begins to wane, doing a few minutes of an activity like jumping jacks or taking a bike ride will help to stimulate dopamine and enable your child to resume focusing on homework. According to ADHD expert Dr. John Ratey, exercise increases levels of dopamine and norepinephrine in the brain, helping to alleviate the inattention associated with ADHD. Exercise can also help regulate emotional control and fidgetiness. Other activities on a dopamine menu can include: eating a snack, listening to music, working on a hobby, journaling, listening to white noise, or listening to a podcast.

Drug therapies for ADHD increase dopamine

The Center for Disease Control and Prevention estimates two-thirds of children are medicated for the treatment of ADHD. The primary medications used to treat the symptoms of ADHD are from a group of drugs known as stimulants. Stimulant medications increase the amount of dopamine in the synapse, the space between neurons, by preventing the removal, or reuptake, of released dopamine. Approximately three million children in the United States take stimulant medications to help them focus, with roughly 60% of children with ADHD treated with stimulants. Although stimulant treatment can improve attention and focus, it will not affect the ability to learn or to apply learned concepts in a child with ADHD.