Myth: ADHD is caused by poor parenting or teaching.
Parents and teachers are popular targets for those who misunderstand ADHD. This myth posits that ADHD would not exist if parents and teachers were more effective at disciplining and teaching children. From this perspective, ADHD is a failure of society, not a brain disease.
Fact: ADHD occurs when genes and toxic environments harm the brain.
Blaming parents and teachers for ADHD is wrong. We know from research studies that many parents of ADHD children have normal parenting skills and even when we train parents to be better parents, ADHD does not disappear. In fact, many parents of ADHD children have a non-ADHD child that they raised with the same discipline methods. If bad parenting causes ADHD, all of the children in the family should have ADHD. Equally important, decades of research studies have shown that genes and toxic environments cause ADHD by harming the brain. I’m not saying that all parents and teachers are perfect. In fact, by teaching parents and teachers special methods for dealing with ADHD can help children with ADHD.

Myth: Watching Television causes ADHD.
This myth hit the media in 2004 when a research group published a paper suggesting that toddlers who watched too much TV were at risk for attentional problems later in life.
Fact: The study was wrong.
Sometimes researchers get it wrong. But fortunately science is self-correcting; if an incorrect result is published, subsequent studies will show that it is wrong. That’s what happened with the ADHD television study. After the first study made such a media splash, several other researchers did similar studies. They found out that the original study had errors and that watching too much TV does not cause ADHD. But, because the popular media did not pick up the later studies, the myth persists. I’m not recommending that toddlers watch a lot of television, but rest assured that, if they do, it will not cause ADHD.

Myth: Too much sugar causes ADHD.
This idea is based on common sense. Many parents know that when their children and their friends have too much sugary food, they can get very active and out of control.
Fact: Sometimes, common sense is wrong.
As a parent, I thought there was some truth to the sugar myth. But when a colleague, Dr. Wolraich, reviewed the world literature on the topic, he found that there have been many studies of the effect of sugar on children. These studies show that sugar does not affect either the behavior or the thinking patterns of children. Having too much sugar is bad for other reasons, but it does not cause ADHD.
 

REFERENCES
Wolraich, M. L., Wilson, D. B. & White, J. W. (1995). The effect of sugar on behavior or cognition in children. A meta-analysis. JAMA 274, 1617-21.

Stevens, T. & Mulsow, M. (2006). There is no meaningful relationship between television exposure and symptoms of attention-deficit/hyperactivity disorder. Pediatrics 117, 665-72.
Evans, S. W., Langberg, J. M., Egan, T. & Molitor, S. J. (2014). Middle School-based and High School-based Interventions for Adolescents with ADHD. Child Adolesc Psychiatr Clin N Am 23, 699-715.

Pfiffner, L. J. & Haack, L. M. (2014). Behavior Management for School-Aged Children with ADHD. Child Adolesc Psychiatr Clin N Am 23, 731-746.