Medically reviewed by Nancy Hammond, M.D. — Written by Neel Duggal
Updated on January 15, 2020
What is ADHD?
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder. People with ADHD have difficulty maintaining attention or have episodes of hyperactivity that interfere with their daily life.
People sometimes refer to it as ADD, but ADHD is the medically accepted term.
ADHD is common. It’s estimated that 11 percent of children have ADHD, while 4.4 percent of adults have the condition in the United States.
ADHD usually begins in childhood. It often continues through adolescence and sometimes into adulthood.
Children and adults with ADHD typically have more difficulty focusing than people who don’t have ADHD. They may also act more impulsively than their peers. This may make it difficult for them to perform well in school or work as well as the general community.
Dopamine transporters and ADHD
Underlying issues with the brain are likely to be the underlying cause of ADHD. No one knows exactly what causes a person to have ADHD, but some researchers have looked at a neurotransmitter called dopamine as a possible contributor to ADHD.
Dopamine allows us to regulate emotional responses and take action to achieve specific rewards. It’s responsible for feelings of pleasure and reward.
Scientists have observed that levels of dopamine are different in people with ADHD than in those without ADHD.
Some researchers believe this difference is because neurons in the brain and nervous systems of people with unmedicated ADHD have lower concentrations of proteins called dopamine transporters. The concentration of these proteins is known as dopamine transporter density (DTD).
Lower levels of DTD may be a risk factor for ADHD. Just because someone has low levels of DTD, however, doesn’t mean they have ADHD. Doctors will typically use a holistic review to make a formal diagnosis.
