• Heredity is one of the key causes of ADHD. Research studies have shown that the disease tends to run in families. However, it is not type-specific. For example, a father who has ADHD of predominantly hyperactive-impulsive type can have a son who has ADHD of combined type.
• Artificial colors added to foods that are regularly consumed by the child or adult can figure in the causes of ADHD, although this has not been significantly proved.
• If the mother has been exposed to toxins during pregnancy, such as active or passive smoking, alcohol and drug abuse, there are high chances of the unborn child developing ADHD due to faulty neuropsychiatric development.