What Causes ADHD: Myths vs. Facts

Though a popular idea, sugar is not a cause of ADHD. According to the National Institute of Mental Health, studies have been conducted on this very topic and found no link. Researchers have studied behavior and learning capability with children who have taken varying amounts of sugar, sugar substitute and placebos and found no link between sugar and ADHD.

A 2012 study out of the Mayo Clinic found that children who had been repeatedly exposed to anesthetic at a young age were twice as likely to develop ADHD. If a child had undergone anesthesia more than two times before the age of three, the risk of ADHD doubled. The research found that the risk does not change with one exposure to anesthesia, but a second exposure jumped the ADHD incidence from 7.3 percent to 17.9 percent.

A 2012 study found that ADHD is actually over-diagnosed in the youngest children in a given class. As ADHD is diagnosed largely by behavior, less mature students were often labeled as having ADHD. The study found that children born in the last month of school enrollment eligibility (December) were 48 percent more likely to be diagnosed with ADHD than children born at the beginning of the year.

A 2010 study out of Cardiff University (UK) discovered that there is a genetic element to ADHD. The study analyzed the DNA of hundreds of children both with and without ADHD. Researchers found that children with a specific genetic segment either duplicated or missing were twice as likely to have ADHD. As Professor Anita Thapar stated, "Now we can say with confidence that ADHD is a genetic disease."

In conjunction with the study on genetics and ADHD, it became clear that there is more to the condition than just bad parenting. With a specific DNA identifier linked to the condition, it is difficult to blame ADHD solely on parenting. The National Institute of Mental Health has conducted numerous studies on the subject and has found that, though environmental factors can influence the prevalence, ADHD is not "caused" by bad parenting.

According to a 2012 study, children born "post-term" – after 42 weeks as opposed to the standard 40 – are more likely to have behavioral problems, including ADHD. Though the exact cause was unknown, theories exist that link the ADHD to insufficient oxygen and nutrients from the placenta after the "placental clock" has gone beyond the normal duration of pregnancy.

During the 2012 study to investigate post-term births, one of the control items was for babies over 4,000 grams. When studying this theory, no correlation was found between a heavy birth weight and ADHD.

A 2010 study showed a link between second hand smoke and the prevalence of ADHD. The study found that "there was "significantly higher rates of attention deficit hyperactivity disorder (ADHD), headaches and stuttering among children exposed to secondhand smoke than those who are not exposed."

The popular Feingold Diet identified food additives as a cause of ADHD. However, a 2011 study by the FDA found that behavioral change "is not due to an inherent neurotoxic property of the food or food components." It did note, though, that the chemicals may cause hyperactive behavior but not necessarily the condition.