Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder. It’s most often diagnosed in childhood or adolescence. In a parent report from 2011, the Centers for Disease Control and Prevention report that close to 11 percent of American children ages 4 to 17 have been diagnosed with ADHD.

However, more than half of children with ADHD continue to experience symptoms as adults. Today, around 8 million adults live with ADHD. Many go on to lead healthy lives with successful careers. Some even become famous.

Here’s a collection of some well-known people who just happen to live with ADHD.

ADHD made schoolwork difficult for Phelps when he was little. He liked to move, acted up in class, and had a hard time getting his work finished. Phelps was diagnosed with ADHD at age 9.

“I [saw] kids who, we were all in the same class, and the teachers treated them differently than they would treat me,” Phelps told People magazine. “I had a teacher tell me that I would never amount to anything and I would never be successful.”

Medication made his symptoms better, but it was in the pool that Phelps found the ability to deal with his disorder. The routine of practice and the soothing effects of the water helped him to cope and excel.

“I think the biggest thing for me, once I found that it was okay to talk to someone and seek help, I think that’s something that has changed my life forever,” he says. “Now I’m able to live life to its fullest.”

At his retirement, Phelps was the most decorated Olympian of all time. He’s won 28 Olympic medals, 23 of which are gold.

This “Dancing with the Stars” performer and professional dancer went public with her ADHD diagnosis in 2009.

“As a professional dancer, I’ve become known for my moves and my career accomplishments, but most people don’t know about another part of my life — I’m an adult with ADHD,” Smirnoff told The Saturday Evening Post.

Smirnoff is able to channel much of her energy into her dancing. She’s a five-time U.S. National Champion and a World Trophy Champion.

“Like most adults, my schedule is very busy. My day is filled with 10-hour dance rehearsals for my television show, teaching choreography, dancing in shows, and constant travel,” she says. “With improvement in my ADHD symptoms, I can focus on finishing what I start.”

This game show host and stand-up comedian is known for his vivacious personality as well as for his disorders. Mandel has both ADHD and obsessive-compulsive disorder (OCD). He grew up with these disorders during a time when they weren’t officially diagnosed or understood.

“Back in the 1960s, when I was growing up, my symptoms didn’t have a name and you didn’t go to the doctor to find out. So, in my case, they were called ‘Howie Mandel,’” Mandel wrote for Additude magazine.

Today, the “America’s Got Talent” host takes medication and attends therapy to help him deal with his disorders.

“After I impulsively revealed that I have OCD on a talk show, I was devastated. I often do things without thinking. That’s my ADHD talking,” Mandel wrote. “Out in public, after I did the show, people came to me and said, ‘Me, too.’ They were the most comforting words I’ve ever heard. Whatever you’re dealing with in life, know that you’re not alone.”

This home improvement guru was always full of energy as a child. Pennington was hyperactive, and he was a distraction to other children in the classroom. Doctors weren’t sure how to treat his behavioral problems at first.

“My mom was studying to be a child psychologist and she went to my elementary school to test the worst kid they had. They were like, ‘Mrs. Pennington, you really don’t want to know who that is,’” Pennington told the Huffington Post.

“They let her observe me through a window and within 20 minutes I stripped naked, wore my desk around, and swung on the blinds. I was just a complete distraction to all the other students.”

Pennington added that doctors gave him antihistamines to make him drowsy. Now, he takes medicine from time to time in small doses, and still sees a psychiatrist. Pennington channels the symptoms of his ADHD into his career and his hobbies.

“Once I figured out I was pretty decent at art and people were interested in hiring me, I realized I had a skill besides injuring myself,” Pennington says. “What’s kind of funny is that I ended up working with power tools to pay my way through art school and still have all my digits.”

This Maroon 5 frontman and host of “The Voice” has come a long way to his success. He wrote for Additude magazine that as a kid, he struggled with what seemed normal to other kids — sitting still, completing work, focusing.

His parents helped him find treatment, but his problems with attention persisted into adulthood.

“I had trouble sometimes writing songs and recording in the studio. I couldn’t always focus and complete everything I had to. I remember being in the studio once and having 30 ideas in my head, but I couldn’t document any of them,” he wrote.

He went back to the doctor and learned that the ADHD hadn’t gone away as he’d grown up. In fact, he still deals with it daily.

“ADHD isn’t a bad thing, and you shouldn’t feel different from those without ADHD,” he wrote. “Remember that you are not alone. There are others going through the same thing.”

Justin Timberlake, the multifaceted singer and actor, revealed in an interview with Collider.com that he has both OCD and ADD.

“I have OCD mixed with ADD,” he says. “You try living with that [combination].”

Since that interview, Timberlake hasn’t spoken about either of his conditions or how the two affect his day-to-day life. But the multiple Grammy and Emmy award winner has clearly found a way to manage his symptoms and live a fulfilling, highly successful life.

The hotel heiress and socialite Paris Hilton revealed that she was diagnosed with ADD as a child in an interview with Larry King.

“I’ve been on medication since I was a child,” she says. “I have ADD, so I take medication for that.”

The Olympic gymnast won hearts across the country with her 2016 gymnastic performance. Her powerful tumbles and gravity-defying beam routines set hearts ablaze and earned her the 2016 Olympic individual all-around, vault, and floor gold medals.

After the Olympics were over, leaked drug tests from the Olympic committee showed that Biles tested positive for methylphenidate. This drug is also known as Ritalin. It’s prescribed to many individuals with attention disorders, including Biles.

“I have ADHD and I have taken medicine for it since I was a kid,” Biles wrote on her Twitter account. “Please know, I believe in clean sport, have always followed the rules, and will continue to do so as fair play is critical to sport and is very important to me.”

When she was first diagnosed with ADHD, singer, songwriter, and artist Solange Knowles didn’t find solace in finally having an answer for her issues. Instead, she visited another doctor for a second opinion.

“I was diagnosed with ADHD twice,” she told BET. “I didn’t believe the first doctor who told me and I had a whole theory that ADHD was just something they invented to make you pay for medicine, but then the second doctor told me I had it.”

Now that she has a diagnosis herself, Knowles says she can see so many symptoms of ADHD in other people in the music business. “The symptoms seem to apply to everyone around me in the industry. Loss of memory, starting something and not finishing it…” she said.

These celebrities are proof that a medical disorder doesn’t have to be a reason for not living a full, happy life. These well-known figures, as well as other many less-famous folks have found ways to thrive with ADHD.

The key to managing the signs and symptoms of ADHD is finding a treatment plan that works and sticking with it.