What causes it? Twin studies have shown that there is a genetic basis for ADHD. True susceptibility genes have yet to be identified, although candidate genes have been proposed. ADHD does tend to run in families: about 25% of the parents of children with ADHD also have the condition or another condition such as depression, substance abuse, conduct disorder in childhood or adult onset antisocial personality disorder. Some families also have a history of bipolar disorder.[1]
Faraone SV. 2000. Genetics of Childhood Disorders: XIX. ADHD, Part 4: Is ADHD Genetically Heterogeneous? Journal of the American Academy of Child and Adolescent Psychiatry; 39(11): 1201-1205.
