Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition that causes hyperactivity and difficulty maintaining attention. It typically begins during childhood and often continues into adulthood. According to the Food and Drug Administration (FDA), 13.2% of boys and 5.6% of girls are diagnosed with ADHD.

The exact cause of ADHD is not known, but it is associated with changes in neurotransmitter activity in certain areas of the brain. Neurotransmitters are chemicals that coordinate the action of the nervous system. 

The Link Between Dopamine and ADHD

The neurotransmitters most closely associated with ADHD are dopamine, serotonin, norepinephrine, and epinephrine. These neurotransmitters have similar chemical structures, and they are formed by interconnected biochemical processes.

The actions of neurotransmitters involved in ADHD are:

• Dopamine, among other functions, helps maintain coordination of voluntary muscle movement (the muscles that you control). It also plays a role in regulating emotions, behavior, motivation, and feelings of pleasure and reward.
• Serotonin is involved with mood and anxiety regulation, sexual function, and digestion. 
• Epinephrine and norepinephrine are involved in maintaining the normal balance of many functions of the body, including the heartbeat and blood pressure.

Research studies examining the metabolic activity of the brain have found that the action of these neurotransmitters is disrupted in people who have ADHD. The changes may be associated with differences in a person's genetic makeup. The neurotransmitter change that is most significant in ADHD is a decrease in dopamine activity. 

Research Into Dopamine Transporters and ADHD

Dopamine transporters are proteins that regulate the action of dopamine by prolonging or terminating the action of the neurotransmitter.

Some studies using functional neuroimaging techniques such as positron-emission tomography (PET) scans have found that ADHD is associated with abnormalities of dopamine transporters in certain areas of the brain. The abnormalities in dopamine transporters vary with age and are impacted by medication.

Dopamine dysfunction in ADHD is associated with a change in the dopamine transporter gene. A genetic change described as the VNTR polymorphism (DAT1 VNTR; rs28363170) is one of the most consistent genetic markers of ADHD.

Additionally, transporters for serotonin, norepinephrine, and epinephrine may have irregularities in people with ADHD as well.

For example, one research study reported an increase in dopamine transporter activity in the striatum (located in the forebrain), decreased dopamine transporter activity in the cingulate (another brain area), and decreased serotonin transporter activity in the striatum and midbrain. Study authors suggest that the inconsistencies could be related to compensatory mechanisms (the body taking actions due to the increased dopamine transporter activity).

Low Dopamine Levels in the Brain

Changes in dopamine levels and dopamine activity are involved in several different medical conditions. 

For instance, dopamine levels are sometimes described as being too high or too low, but research suggests that the disorders are caused by more complex changes than high or low levels of dopamine. 

In addition, the effects of these different conditions can also be related to alterations in dopamine activity in specific regions of the brain.

Many of the conditions associated with dopamine alterations are also associated with changes in other neurotransmitters as well, which adds to the complexity of the disorders and their treatments. 

Conditions associated with dopamine changes in the brain include:

• Addictive behavior: Substance use problems and other addictive behaviors are associated with a physical and psychological craving for the effects of dopamine. A dopamine surge in response to certain actions (such as taking a substance or engaging in a behavior) may contribute to feelings of reward, which can have an effect in addiction. This makes it extremely difficult to stop certain behaviors and activities, such as gambling, video games, social media, and drug use. 
• Parkinson’s disease: Parkinson’s disease is a neurodegenerative disease associated with a decline in dopamine action in the brain. Parkinson's primarily causes motor symptoms, including tremors, rigidity, and problems with balance. Many of the treatments for this condition work by increasing dopamine levels in the brain. 
• Depression: Depression is primarily associated with altered regulation of serotonin. Many antidepressants work by increasing the effects of serotonin in the brain. 
• Schizophrenia: This disorder is linked to excess dopamine activity in the brain. The symptoms include hallucinations, delusions, and social withdrawal. The medications that are used to treat symptoms of schizophrenia often work by inhibiting the action of dopamine. 

Other conditions that have been linked to altered dopamine action include Tourette’s syndrome and binge eating disorder. 

ADHD Treatment

The treatments used for managing ADHD include behavioral therapy, counseling, and medications. Many children and adults benefit from using strategies to stay organized and on task. Getting regular physical exercise and sleep can be beneficial as well.

ADHD Treatments That Increase Dopamine

Prescription stimulants are often used to treat ADHD. These medications increase the levels of dopamine in the brain. However, they can cause side effects, such as insomnia and weight loss.

Stimulants used to treat ADHD include:

• Ritalin or Concerta (methylphenidate)
• Adderall or Vyvanse (dextroamphetamine)

Other ADHD Treatments

Several medications approved for treatment of ADHD are not considered stimulants.

Non-stimulant ADHD medications include:

• Strattera (atomoxetine): Selective norepinephrine reuptake inhibitor
• Intuniv (guanfacine): Central-acting alpha-2 adrenergic receptor agonist
• Kapvay (clonidine): Central-acting alpha-2 adrenergic receptor agonist

Summary

Attention deficit hyperactivity disorder (ADHD) is a condition that causes problems with attention and behavior. Some of the treatments help manage this condition have an effect on dopamine or other neurotransmitter action in the brain, and the condition has been linked to changes in dopamine levels in some regions of the brain.

There is also evidence that alterations in serotonin, epinephrine, and norepinephrine may have an effect as well. Research about the biochemical changes and structural brain changes in ADHD is ongoing. 

A Word From Verywell

If you or your child has ADHD, it’s important to know that there are effective treatments. A multidisciplinary approach that includes lifestyle changes, therapy, and medication is usually recommended.

Changes in dopamine activity are involved in ADHD, but the link is not straightforward, and it might not be consistent at different ages or at different stages of the disorder.