ADHD’s Genetic Link

What causes attention-deficit hyperactivity disorder – ADHD? Research in the English medical journal, The Lancet, says it’s not too much sugar, bad diet, or poor parenting. Professor Anita Thapar, lead author of the study, says it’s likely genetic.

Thapar and her group of scientists at Cardiff University in Wales compared 366 children with ADHD to 1,047 kids without ADHD. In particular, the researchers examined differences in the children’s DNA. They found that kids with ADHD were more likely to have small segments of DNA that were duplicates or missing (copy number variants or CNVs — either a deletion or duplication of genetic material).

“We hope that these findings will help overcome the stigma associated with ADHD,” Professor Anita Thapar, the study’s lead author, said in a written statement. “Too often, people dismiss ADHD as being down to bad parenting or poor diet. As a clinician, it was clear to me that this was unlikely to be the case. Now we can say with confidence that ADHD is a genetic disease and that the brains of children with this condition develop differently to those of other children.”

While being media friendly, Thapar’s last statement is a stretch in relation to her research. People and the media love statements that provide seemingly conclusive answers.

Let’s go beyond the media hype that says this research concludes there is a definite genetic link. The researchers really only say there seems to be a possible “genetic link.”  However, their research did not conclude that it is purely or even primarily genetic. What they truly are saying is that this study is evidence that ADHD is not purely social.

The authors conclude:

“Our findings provide genetic evidence of an increased rate of large CNVs in individuals with ADHD and suggest that ADHD is not purely a social construct.”

This is logical because only 15% of the research subjects with ADHD demonstrated increased CNVs. So is it safe to conclude that genetic makeup may contribute, at least in some particular cases, to ADHD? Yes, but to be clear,  this research did not conclude that it is entirely genetically based and was only partially genetically based in a small segment of their study population. This is very similar to other genetic research.

Why is it, if ADHD is genetically based, at least in part, that 30% don’t have it as adults when diagnosed as a child? What happened? Where did it go? This is what is most  important to parents and professionals.

Epigenetic theory, now being widely embraced by the scientific community, maintains that human development  includes both genetic origins of behavior and the direct influence that environmental forces have on the expression of those genes (nature/nurture). Epigenetic theory regards human development as a dynamic interaction between these two influences.

Simply put, how our genes express themselves is greatly impacted by environment. This is likely why, over time, 30% of children don’t display symptoms as adults. The brain changes, rewires, or (a radical version of epigenetic theory) their genes change.

Do tools exist to do this? Yes. See www.playattention.com.

If I may quote Dr. Theodore Dalrymple, “What seems to have happened is that parents have lost the awareness that they had for decades – if not for centuries – that concentration and self-discipline do not come naturally to children, and have to be taught (as well, sometimes, as enforced).”

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