ADHD is a neurobehavioral
disorder that affects approximately 5.2 million children in the United States (CDC, 2012). ADHD affects the way in which a person’s brain processes information and,
in turn, influences behavior. The exact cause of ADHD is unknown. However, researchers
believe that genetics, nutrition, brain development, and other factors play a significant
Genes and ADHD
There is strong evidence
that a person’s genes influence ADHD. In the few studies conducted with twins,
researchers have found that ADHD runs in families (NIMH, 2012). It has been found to especially
affect close relatives of people with ADHD. If your mother or father has ADHD,
you and your siblings are more likely to have the disorder.
No one has yet been able
to determine exactly which genes influence ADHD. Some studies, however, have
discovered a connection between ADHD and the DRD4 gene (Holmes et al., 2002). These studies have led expert to believe this gene plays a
role in the development of the condition. Still, researchers believe there is
more than one gene responsible for ADHD.
It is important to note that
ADHD has been diagnosed in individuals who have no family history of the
condition. A person’s environment and a combination of other factors can also influence
whether or not you develop this disorder.
Neurotoxins Linked to ADHD
Researchers have also found a
connection between ADHD and certain common neurotoxic chemicals, namely lead
and certain pesticides. Lead exposure in children can hamper brain development,
leading to learning disorders including ADHD.
Exposure to organophosphate
pesticides has also been linked to ADHD (Bouchard et al., 2010).
These pesticides are chemicals sprayed on lawns and agricultural products. They
include corn, apples, pears, grapes, berries, and peaches. Children who had
high levels of these pesticides in their systems were in some cases twice as
likely to have ADHD as children who did not. Organophosphates are believed to disrupt
the neurotransmitter acetylcholine in a child’s developing brain. This key
neurotransmitter is responsible for controlling memory, attention, awareness,
perception, reasoning, and judgment.
Smoking and Alcohol Use During Pregnancy
Perhaps the strongest link
between the environment and ADHD occurs before a child is born. Research
consistently shows a strong link between smoking and alcohol use during pregnancy
and ADHD. According to a recent study by Washington University in St. Louis, if
a mother is genetically predisposed to the disorder and smokes during
pregnancy, her child is six to nine times more likely to develop ADHD or have more
severe ADHD symptoms (Neuman
et al., 2007). Nicotine can affect the same dopamine receptors influenced by
the DRD4 gene.
Nutrition and ADHD Symptoms
A 2007 study by British
researches showed that children who consume foods with artificial coloring or a
sodium benzoate preservative were more hyperactive than those who did not
consume these additives (McCann et al, 2007). Foods with artificial coloring include most processed and
packaged snack foods. Sodium benzoate preservative is found in fruit pies,
jams, soft drinks, and relishes. Researchers have not determined exactly how
these ingredients influence ADHD, only that they appear to exacerbate its
Common Myths: What Doesn’t Cause
There are many myths about what causes ADHD. Research has found no
evidence that ADHD is caused by consuming excessive amounts of sugar, TV
watching, video game playing, poverty, or poor parenting. These factors can
worsen ADHD symptoms. However, none of these factors have been proven to directly