By Mignon Fogarty
This article originally appeared in ADDitude Magazine
On the surface, Peter Anderson and his son, Justin,
could not be more different. Peter, 54, is the picture of success:
affable president of his high school class, economics graduate of the
University of Virginia, and inventive founder of a thriving advertising
and marketing firm in Connecticut.
Justin’s family believes he is just as smart but
his path has been more difficult. He was the one who couldn't sit still
in school, who got into fights, and who at 20, still struggles
academically. No surprise: Justin has attention deficit hyperactivity
disorder (ADHD).
The big surprise is that Peter has ADHD too. "I didn't
even know that I had it until one day I was sitting in a psychologist's
office [for Justin’s treatment] and he said it is hereditary," Anderson
says. Soon, he and his family put the pieces together: His lack of
organization, tendency to lose things, and 12-track thinking process
were all symptoms of ADHD. They believe Peter’s late brother had ADHD
too.
But the Anderson family history wouldn't surprise
researchers. Studies of identical twins (who share the same genes)
suggest that up to 80 percent of the risk of ADHD is genetic. Like
Justin Anderson, children with one ADHD parent have a 25 to 30 percent
chance of developing the condition, according to Susan Smalley, Ph.D.,
a medical geneticist at UCLA's department of psychiatry and co-Director
of its Center for Neurobehavioral Genetics. That's about five times the
risk of a child whose parent doesn't have ADHD. And if one child has
ADHD, siblings are more likely to be affected.
Like the Andersons, different family members are not
necessarily affected in the same way. Peter’s case is mild, controlled
by self-taught coping strategies and organizational assistance from his
wife. Justin’s more severe ADHD has responded only partly to medication
and behavioral interventions.
Justin's mother and Peter's wife, Joyce, believes
personality also plays apart. "Peter is a consensus builder," she says.
"Justin was always the rebel."
Had Peter Anderson fathered daughters instead of sons,
the familial pattern may not have held, since girls are less likely to
be diagnosed with ADHD than boys. Although it is possible that boys and
girls get ADHD at the same rate, and that girls are just more difficult
to diagnose, it could well be that boys really do get ADHD more often
due to genetics and biology.
One hypothesis is that a gene or genes on the X
chromosome increase the risk of developing ADHD; boys, then, have an
increased risk because they have only one X chromosome whereas girls
have two. However, researchers have not yet identified a specific gene
for ADHD on the X chromosome.
Hormones may count too. "Hormones might modify gene
expression," says Smalley. "This could be one way we get differences
between boys and girls." Gene expression is the process of translating
genes into proteins, the molecules that do most of the work in the body.
One protein known to play a role in ADHD is dopamine,
the chemical released by neurons in the brain to communicate with other
neurons. Most of the medications used to treat ADHD act on the dopamine
transporter, which assists neurons with dopamine messaging. Researchers
are studying the dopamine transporter gene to see if defects increase
the risk of having ADHD.
Smalley says that although mutations in
dopamine-associated genes get a lot of attention, so far they have been
shown to only slightly increase ADHD risk. "The effect has not been
replicated from study to study," she says. Still, she's confident
stronger ADHD risk genes will be identified within the next few years.
In the meantime, awareness that ADHD runs in your
family can be valuable. Twenty years ago, doctors couldn't tell
Justin's parents how to help him. "We spent many years, went to many
specialists, and spent many thousands of dollars before we were able to
figure out that my son had ADHD and how to treat it," Anderson says.
Today, it's different. "Unfortunately, you don't get
an owner's manual when the baby arrives," he says. "But if you can get
a road map of what might occur and what to prepare for, that would be
helpful."
Smalley agrees. "You want to pay attention and look
for early signs, and/or get screening using behavioral observations to
pick up ADHD and an early age," she says. "You generally have a better
outcome the earlier you treat something."
