Genetic tests are useful for certain inheritable disorders, like cystic fibrosis and sickle cell anemia. But don't send in a swab of your child's saliva and a check for hundreds of dollars for a genetic test for behavioral problems like attention deficit hyperactivity disorder.
A genetic test examines the DNA or deoxyribonucleic acid in a person's cells for any abnormal genes, or analyzes the characteristics, number, and arrangement of chromosomes. Results of genetic tests depend on the type of test done, but they are usually done in order to diagnose a rare inherited disease, predict the likelihood of inheriting a disease, determine whether or not you are a carrier of a disease, or provide information on the severity of an inherited disease. There is enough evidence to demonstrate the relationship between genetics and ADHD; if one parent or both parents have ADHD, their children are more likely to inherit it. However, there is no single genetic test that can determine whether or not a child has ADHD.
There are three reasons for this. Unlike other inheritable disorders, in which a blood test can identify a particular condition, there is no specific gene that carries ADHD. Although researchers are still trying to identify which combination of genes may make a person predisposed to the disorder, so far no single gene been found. Hence, a genetic test is useless if the intention is to diagnose the child with the disorder. Secondly, there is no single test that can determine whether or not a child has ADHD. Even if there is a genetic basis for the disorder, it is not a guarantee that a child will develop ADHD. This brings us to the third point. Genetic testing cannot be used to predict inheritability, because ADHD is the end-product of complex interactions between the environment and a particular genetic profile. If a test says a child has a 30% risk of developing ADHD, it also means he has 70% of not developing it! A child who is at risk of developing ADHD because he has the a possible genetic susceptibility will not experience the disorder if he or she lives in a toxin-free environment, receives a nutritious balanced diet high in omega-3 fatty acids and low in carbohydrates, gets plenty of movement and exercise, and has proper structure at home and in school.
All that being said, advances in functional medicine and nutrigenomics – the science of how nutrition affects our genes – have shown that children suffering from ADHD and other related disorders have slight genetic variations called Single Nucleotides Polymorphisms. Those small variations may make a child more susceptible to toxic exposures or food allergies. His or her metabolism (such as ability to detoxify or enzyme activation) may be slower or faster, or require different levels of cofactors to function properly. For example, one study showed that children with autism needed 10 times more of some B vitamins in order to activate a specific enzyme to the same degree as children without autism.
So some type of genetic testing may be useful to understand those subtle variations and design a care plan that is truly unique for your child. As always, those tests should only be ordered by health care practitioners who have been specially trained in interpreting them.