The National Institute of Mental Health notes that scientists aren’t entirely sure what causes attention deficit hyperactivity disorder. Anything from genes and brain injuries to low birth weight and exposure to environmental toxins at a young age may play a role.
However, of these variables, experts tend to agree that genetics is the most likely link. But this isn’t to say the other factors go entirely by the wayside. For example, one study, published in Human Genetics, mentions that although ADHD is “highly heritable,” it’s a “multifactorial disorder, in which many genes, all with a small effect, are thought to cause the disorder in the presence of unfavorable environmental conditions.”
The Centers for Disease Control and Prevention reinforces this notion, outlining that in addition to the “important role” genetics plays in ADHD, other possible risk factors and causes may include brain injury, exposure to lead during pregnancy or at a young age and premature delivery.
According to James M. Swanson, professor of pediatrics at the University of California, Irvine, whether genetics is the main reason a person develops this disorder remains “a tricky question.” He explains that while ” ADHD does seem to run in families” and that the “statistical estimate of heritability is very high,” he stresses that this does not necessarily mean that all ADHD cases have a genetic basis. “Interpretation of estimates of ‘heritability’ is complicated.”
“Simply put, the etiology of ADHD is complex and can involve multiple causes,” says Russell A. Barkley, clinical professor of psychiatry, Medical University of South Carolina. “To date, all of the major ones fall in the realm of neurology and genetics — biological causation — with no evidence that social factors alone can account for the condition.” He explains that head trauma or other neurological injuries, alcohol use during pregnancy, significant premature birth and…