In The Blood: The Genetic Basis For ADHD

These days, it’s hard to remember that ADHD was once an ill-defined, poorly-understood construct that many parents and even doctors believed to have little basis in medical fact. Today, ADHD is one of the most widely-studied and heavily-diagnosed behavioral disorders in existence, but there remains considerable disagreement as to its root causes. One theory that now appears to be supported by scientific evidence is that the incidence of ADHD and related disorders can be predicted by certain gene combinations.

What Is ADHD?

Unlike some other “diseases,” ADHD does not have a hard-and-fast diagnostic test. Rather, Attention Deficit Hyperactivity Disorder, as it’s known, is typically thought of as an amalgamation of symptoms like loud outbursts, short-term memory problems, poor concentration skills, and the like. The vagueness of many of the disorder’s symptoms lead to frequent misdiagnoses: a recent Michigan State University study estimates that between 900,000 and 1,000,000 children may have been inaccurately informed that they have the condition since ADHD was first recognized.

The Spectrum

ADHD’s vagueness is unfortunate for two principal reasons. First, doctors often rush to diagnose ADHD in questionable situations in order to begin children on mood-altering drug regimens, with serious potential consequences for affected kids’ learning abilities. Second, ADHD resembles other, more disruptive behavioral disorders like autism and schizophrenia. Autistic or schizophrenic children who incorrectly receive a less-serious ADHD diagnosis may not get the help they need right away.

Implications for Treatment

What exactly does all this have to do with the genetic basis for ADHD? For starters, while the gene combinations that predict ADHD are complicated and vary considerably from person to person, it appears that they share many nucleotide sequences with genes that predict autism and schizophrenia. In other words, an “ADHD-positive” child who possesses a certain version of the “ADHD gene” may be more likely to develop schizophrenia later in life. You can bet that the scientific community is going to pour billions into researching the genetic links between ADHD and other behavioral disorders in the coming years, with potentially revolutionary results.

Other Genetic Causes of ADHD

In addition to the “copy-number variants,” which appear to predict ADHD as well as autism and schizophrenia, there are several other potential genetic causes of ADHD. Each has its own implications for treatment:

  • Kleinfelter Syndrome: A fairly common genetic disorder that imparts an extra ‘X’ chromosome in boys and men. It is associated with disruptive and erratic behavior reminiscent of ADHD.
  • Jacob’s Syndrome: A less common disorder that imparts an extra ‘Y’ chromosome in men and boys. Its symptoms are similar to those of Kleinfelter.
  • Fragile X Disorder: A deficiency in an important X-chromosome gene affects the ability of “Fragile X” sufferers to concentrate and learn by memorization, which may lead to disruptive classroom behavior.

Although it’s clear that genetics plays an important role in the expression of ADHD, more work remains to be done on the subject. In particular, the connection between “ADHD genes” and the incidence of autism and schizophrenia needs to be explored. Related genetic disorders like Kleinfelter Syndrome and Fragile X Disorder may offer clues as well. For now, doctors hold out hope that one day ADHD will be as treatable as once-formidable childhood diseases like whooping cough and the measles.

Deborah Mobley blogs about childhood ADHD. If your child has ADHD, or if you suspect that he does, Deborah recommends checking out this Site for more information, including how contemplation can help regulate the symptoms of ADHD.