ADHD is Genetic? Not so Fast.Heather Turgeon
This week we learned that scientists have found the first direct evidence of the genetic roots of ADHD. Research conducted by scientists at Cardiff University and published in the Lancet report findings that, for the first time link gene sequences and ADHD.
The researchers were looking for “copy number variants” – chunks of DNA code that were either deleted or duplicated in the genome. They found that children with ADHD were twice as likely to have the variants when compared to the control group of typically developing kids.
More impressively, the kids with ADHD who also had an IQ lower than 70 were 6 times as likely as the control group to have copy number variants.
Direct evidence that ADHD is a genetic disorder? Let’s not get ahead of ourselves.
First of all, the increase in the rate of deleted or copied DNA went from 7 percent in controls to 14 percent in kids with ADHD. That’s an interesting finding, but it’s far from comprehensive. As Johnjoe McFadden points out in the Guardian, if you turn the numbers around, that means that 7 out of 8 kids with ADHD didn’t have these variants at all.
And the IQ finding is also intriguing, but, as with all psychiatric conditions, it’s hard to know exactly what you’re pointing to — genetic information that leads to difficulty focusing, or DNA coding for some other part of the brain involved in information processing or learning.
It’s not to discount the study, because it’s a step towards uncovering the roots of a disorder that clearly has a biological basis. We already knew that ADHD was highly heritable — but now we’ve put some flags up on the genetic map that will help scientists figure out where to look from here.
It’s similar to the story of autism’s genetics: from a massive number of genes, to an endlessly complicated system of neurons, to the behavior you see on the outside — it’s way too complex to think we’ve got the answers yet.
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