Dr. Russell Barkley

to let's just focus on behavior.

So hyperactive, inattentive, impulsive behavior became the holy trinity of ADHD.

And we stopped speculating about etiology for a while because we didn't really have a lot of hard evidence other than by inference.

Brain injuries cause this syndrome.

Therefore, people who show the syndrome, ergo must have a brain injury of some kind.

But it was just that kind of logic.

But it took, you know, neuroimaging to come around in the 1990s, followed by molecular genetics and all the studies on inheritance.

And now we link the two.

We study the effects of genes on brain networks now.

And it's all just really come full circle.

But that's when the behavior became the focus rather than the brain injury.

Now, of course, we blend them all together.

Yeah, I'll try to oversimplify because let me tell you, it is so complicated that I have trouble keeping up with it.

I mean, you really have to specialize in each of these areas, whether it's brain microstructure or white matter or, you know, neuroimaging or functional connectivity.

They're becoming almost specialties in themselves.

But let me give you the grand picture, you know, from 30,000 feet.

you really have two essential domains of causation here.

One is genetics, and the other is neurological injury-producing maldevelopment.

And I'll just very quickly, I'm going to oversimplify.

About two-thirds to three-quarters of all ADHD cases fall in the realm of genetics.