What causes ADHD?

There is no single "cause" of ADHD, and no simple test for the condition.

The exact mechanisms involved in the development of ADHD are not fully understood, but there is a lot of evidence for a biological cause, and for several key contributing factors. The importance of these different factors probably varies from child to child.

Known factors are:

Genes and inheritance

  • It has been suggested that there are both genetic and environmental factors implicated in whether or not a child will develop ADHD; further work is needed to establish the precise nature of current findings.

Brain processes

  • Studies using brain scans have revealed differences in the development, structure and functioning of the brain in people with and without ADHD.
  • Changes involving some of the chemical messengers in the brain – dopamine, serotonin and noradrenaline – are thought to be involved in ADHD.

Environmental factors

  • Exposure to alcohol or smoking during pregnancy
  • Brain injury during pregnancy
  • Low birth weight




Visit our resource centre for useful information and helpful activities for parents, teachers and teenagers living with ADHD.