Understanding A.D.H.D.

This morning, my colleagues at The Times Magazine published a remarkable cover story by Paul Tough about a surge of A.D.H.D. cases in the United States — and the way we treat them. Today, 23 percent of 17-year-old boys have received a diagnosis of attention deficit hyperactivity disorder. The number of prescriptions rose nearly 60 percent in a decade. You almost certainly know people who take these stimulants.

Why is this happening? One thing I love about Paul’s story is that it’s partly a tale about how science is made and changed. Researchers in the 1930s saw immediate benefits when they treated jumpy kids with amphetamines. Eventually, doctors crafted a diagnosis that could explain distracted and excitable personalities, and a consensus formed about how to treat them. Paul’s story describes how a few scientists have come to challenge that consensus — and some of the fundamental ideas behind A.D.H.D.

For today’s newsletter, I spoke to Paul about his reporting.

What got you interested in this story?

I’ve been writing for decades about education and children, and I now have two boys of my own. A few years ago, I began to notice how many families I met were struggling with their kids’ attention issues. Attention was something I worried about in my own children — and in myself, too. But I didn’t know much about the science behind attention. So I started talking to scientists. When I did, I discovered they had a lot of big unresolved questions.

What is A.D.H.D., and why is it so tricky to define?

There is no biological test for A.D.H.D. So it has to be diagnosed by its symptoms, and those symptoms are sometimes hard to pin down. One patient’s behavior can look quite different from another’s, and certain A.D.H.D. symptoms can also be signs of other things — depression or childhood trauma or autism. Take a child who is constantly distracted by her anxiety. Does she have A.D.H.D., an anxiety disorder or both?

So A.D.H.D. may not be a clear, distinct medical disorder with defined boundaries — something you either have or don’t have?

Increasingly, the science shows that the condition exists on a continuum, and there is no clear dividing line between people who have A.D.H.D. and people who don’t. For many kids, A.D.H.D. symptoms fluctuate over time — worse one year, better the next — and those fluctuations may depend on their external environment as much as their internal wiring.