A study just published in The Lancet offers direct evidence that attention deficit and hyperactivity disorder (ADHD) can be attributed to genetics. While many had suggested this fact and it was known that ADHD could be inherited, no specific gene has been previously identified.
According to CNN, Dr. Robert Marion, chief of genetics and developmental medicine at the Children's Hospital at Montefiore and Albert Einstein College of Medicine, who was not involved in the study says, "This tells us that there is a biological marker that tells us that this person is susceptible to develop this disease." It's important to note though that just as there are genes that predispose a person to violence or cancer, possessing this genetic abnormality is no guarantee that a person will develop it.
In the study, led by Dr. Nigel Williams at the Cardiff University School of Medicine in Wales, 1,047 children who do not have ADHD and 366 who do were analyzed. The children with ADHD have more pieces of DNA that are either missing or extraneous in their chromosomes known as copy-number variants. In the ADHD diagnosed children, they had more rare, large copy-number variants than those who did not have ADHD.
These same variants have been previously associated with other neurological disorders such as schizophrenia, epilepsy and autism. The study suggests a shared biological basis between ADHD and these conditions. Dr. Marion says that based on this discovery, testing can eventually be developed to test a person's susceptibility to ADHD and other neurological conditions, but that these tests are a long way off.
Considering that an analysis by economist Todd Elder at Michigan State University suggested that about 900,000 children in the US have been misdiagnosed with ADHD, a biological basis for which physicians can test would be a welcome addition to ADHD analysis.