Dr. Russell Barkley

You know, you've got the acquired cases, and then you've got the other two-thirds to three-quarters that came by it honestly, so to speak, genetics.

Most of those people inherit this behavior pattern in their families.

It's there as it was in my family, and it gets passed along.

However, we have now learned that about 10% of all cases of ADHD are due to new mutations occurring in the parent's sperm and eggs that are not present in the parent's blood.

So if I did a blood sample, I would not see these mutations.

But if I sample your sperm or if I look at your child, I will find the mutations in that baby and you and your spouse don't have them unless I look at eggs and sperm.

Now, how is that happening?

Because the longer you wait to have children,

the more your gametes, as they're called, your eggs and sperm, are likely to suffer mutations from just surviving, from radiation, from chemicals, from external trauma to male testes and things like that, you are racking up mutations.

And if you wait a decade to have children from age 20 to age 30,

then you now have eight times more mutations in your eggs and sperm, but particularly in your sperm, males are more likely to have those, and those get passed along to your child.

Now, you say, well, so what?

Well, it turns out that the genes most likely to mutate under these circumstances

are the genes for self-regulation, language, and sociability.

So guess what goes up?

Autism and ADHD.

The longer men and women wait to have children, those disorders begin to rise in frequency.

So some of the rise we've seen in both of those conditions over the last 20 years has been the shift in delayed parenthood

As a result of people wanting to have it all, have the job, have the career, have the house, and then we'll have our kids in our 30s.

So, you know, I understand that's complicated.