How is ADHD diagnosed? How can you tell if you or someone you know has the condition?
Many symptoms of ADHD are common to most children, which means the condition can be difficult to accurately diagnose.
ADHD is generally diagnosed well before teenage years, with the average age of diagnosis being seven-years-old.
What percentage of the world's population has ADHD?
Although the vast majority of medical professionals agree that attention deficit disorder does exist, there is still widespread disagreement about how many people qualify for a specific ADHD diagnosis.
In 2013, ADDitude Magazine revealed ADHD is more common than previously thought.
Statistics released by the Center for Disease Control and Prevention (CDC) showed up to 11 percent of American children - aged between four and 17 - have been diagnosed with the hyperactivity disorder at some point in their lives.
According to Health Direct, roughly one in 20 Australian children shows symptoms of ADHD.
Every Day with ADHD reports between five and 10 percent of Australia's population are diagnosed with ADHD at some point.
It is more common in boys, and while most kids grow out of it adult ADHD sometimes persists until much later in life.
New Idea takes a look at 12 famous people with ADHD and how they've turned their attention deficit disorder into an advantage.
Talent clearly runs strong in the Knowles family.
Beyoncé's younger sister Solange Knowles has won numerous accolades including a coveted Soul Train Award, has been writing songs since she was nine-years-old and even temporarily stepped in to Destiny's Child when she was just 15.
In an interview with Respectability, Solange revealed she was diagnosed with ADHD twice because the first time, she didn't believe it.
"The symptoms seem to apply to everyone around me in the industry. Loss of memory, starting something and not finishing it..." she said.
Solange also told Health Central that people sometimes think she's high when she's completely sober sue to her high energy and "sporadic speech".
The mother-of-one has become a vocal advocate for the disorder.
Canadian comedian and TV host Howie Mandel has long been open about his lifelong battle with a variety of mental health issues, including ADHD and obsessive compulsive disorder.
In an op-ed for ADDitude Magazine, the presenter wrote: "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'".
Nowadays, the America's Got Talent host takes medication and goes to regular therapy sessions to help him cope with his ADHD diagnosis and other issues.
Maroon 5 frontman Adam Levine struggled with attention deficit disorder as a child, and his problems continued well into adulthood.
The Voice star previously told Additude Magazine he found things like sitting still and doing homework extremely difficult in his youth, and even had trouble writing songs and committing to time in the recording studio in more recent times.
"I remember being in the studio once and having 30 ideas in my head, but I couldn't document any of them," he said.
Levine also noted: "ADHD isn't a bad thing - you shouldn't feel different from those without ADHD. Remember that you are not alone. There are others going through the same thing."
American hotel heiress Paris Hilton shocked fans by revealing she had been diagnosed with attention deficit disorder as a child.
Speaking to US TV host Larry King, the socialite said: "I've been on medication since I was a child."
United States Olympic swimmer Michael Phelps was diagnosed with ADHD as a nine-year-old, after he struggled to concentrate at school and found homework difficult.
Phelps told People Magazine: "I saw kids who - we were all in the same class - and the teaches treated them differently than they would treat me. I had a teacher tell me that I would never amount to anything and I would never be successful."
Phelps - who went on to win a staggering 23 Gold Medals during his Olympic career, making him arguably the greatest Olympian of all time - explained his experience in a campaign for Child Mind Institute's Speak Up for Kids.
"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. Now I'm able to live life to its fullest."
He also credits swimming for helping him focus his attention and ground him.
In 2008, American singer turned actor Justin Timberlake opened up to Collider Magazine about living with adult ADHD.
"I have OCD mixed with ADD - you try living with that," he said.
ADDitude notes he doesn't often speak about attention deficit hyperactivity, but the disorder hasn't stopped JT from cementing a career as a global superstar!
American athlete Simone Biles - the most decorated gymnast in history and arguably the greatest gymnastic Olympian of all time - was forced to address her ADHD when hackers leaked confidential records about her use of prescription drugs which critics branded stimulant medications to enhance her performance.
The 22-year-old told ESPN at the time: "I have ADHD and have taken medication for it since I was a child...having ADHD, and taking medication for it is nothing to be ashamed of - nothing that I'm afraid to let people know."
Harry Potter icon Emma Watson is well known for her wit, intelligence and overall incredible talent.
Emma has never publicly addressed the subject, but according to Alux she has been medicated for ADHD since childhood.
Emma acts as a UN Goodwill Ambassador, is an outspoken feminist and champion of equal rights and has starred in a vast array of box office smashes including the real life reboot of Disney's Beauty and the Beast.
Seven time Grammy award winner Will.i.Am has spoken many times about his ADHD and how he calms his mind and focuses his attention.
The former Black Eyed Peas star revealed music is his best form of therapy.
Extreme Makeover host Ty Pennington was diagnosed with attention deficit hyperactivity disorder as a child.
The TV host manages his ADHD with stimulant medication, according to ADDitutde, and credits his mother Yvonne for showing him his condition could be the secret to his success.
American Dancing with the Stars pro Karina Smirnoff wasn't properly diagnosed with ADHD until well into adulthood.
The dancer told ABC News she manages her "inattention and impulsivity" with Vyvanse, and channels her high energy levels into her art.
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American political analyst James Carville helped President Bill Clinton reach the White House in 1992 with razor sharp focus and adaptability that comes from his ADHD.
But before his stellar career in statesmanship, Carville dropped out of college due to struggles with his attention deficit disorder.
He first spoke publicly about his condition during an interview with CNN in 2004, and since then has become an ambassador for Children and Adults with Attention Deficit Hyperactivity Disorder.