The exact causes of ADHD are not known, and there is no single cause.
Studies have shown that ADHD symptoms are related to biological features in the brain. It is thought that genetic and environmental factors can interact to cause changes in brain development and function.
- Neurophysiology: It includes differences in brain anatomy, electrical activity and metabolism.
- Genetics: Research shows that ADHD often runs in families. Researchers are currently working on identifying which genes are involved.
- Drug use during pregnancy: Research has linked ADHD to smoking, alcohol and cocaine use during pregnancy.
- Lead: Some studies have shown that pre-schoolers who were exposed to lead (in certain types of paint or plumbing) had a higher risk of developing ADHD.
- Brain injury: Some children with brain injuries show behaviour that resembles ADHD; however, most children with ADHD have no history of brain injury.
- Lack of early attachment: If your child didn’t bond with a parent or caregiver as a baby, they can develop inattention and hyperactivity.
- Childhood post-traumatic stress disorder: a child with this disorder may have symptoms similar to ADHD, but will need different treatment.
Poor sleep during the night can cause trouble concentrating the following day. It is thought that one third of children with ADHD might have sleep apnoea (a blocking of the airway during sleep), but it's not clear whether sleep apnoea is a cause of ADHD. If your child often snores, this might be a symptom of sleep apnoea and may be contributing to the problem.
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Last reviewed: September 2018