Attention Deficit Hyperactivity Disorder: Causes of ADHD

Medically Reviewed by Smitha Bhandari, MD on May 15, 2023
2 min read

No one knows exactly what causes ADHD, but certain things are known to play a role.

ADHD runs in families. Anywhere from one-third to one-half of parents with ADHD will have a child with the disorder. There are genetic characteristics that seem to be passed down.

If a parent has ADHD, a child has more than a 50% chance of having it. If an older sibling has it, a child has more than a 30% chance.

Children born with a low birth weight, born premature, or whose mothers had difficult pregnancies have a higher risk of having ADHD. The same is true for children with head injuries to the frontal lobe of the brain, the area that controls impulses and emotions.

Studies show that pregnant women who smoke or drink alcohol may have a higher risk of having a child with ADHD. Exposure to lead, PCBs, or pesticides may also have a role.

Researchers believe that some toxins may interfere with brain development. That, they say, could lead to hyperactivity, impulsive behavior, and trouble paying attention.

Although it’s been debated, research does not show that ADHD is caused by eating too much sugar or watching a lot of TV.

Other factors that have largely been ruled out as root causes of ADHD include:

  • Parenting styles. There are techniques that parents can use which help support a child who has ADHD, though.   
  • Diet. A healthy diet is good for the brain, but no particular food or dietary pattern has been shown to cause ADHD.
  • Playing video games. There is no evidence that playing video games causes or worsens ADHD. At the same time, some kids with ADHD may be drawn to fast-paced games on the screen. Children with ADHD may “hyperfocus” while playing video games, which can lead to spending too much time playing video games. So while the games themselves don’t cause ADHD, they’re something that parents may need to limit, especially in children with ADHD.
  • Poverty
  • Stress or unstable

Studies show that brain chemicals, called neurotransmitters, don’t work the same in children and adults with ADHD. There also tend to be differences in the way nerve pathways work.

Certain parts of the brain may be less active or smaller in children with ADHD than those without the disorder.

The brain chemical dopamine may also play a role. It carries signals between nerves in the brain and is linked to movement, sleep, mood, attention, and learning.