LAND O'LAKES, Fla. -- When Ellen Mejias got the call from her daughter's first-grade teacher, she couldn't believe it.
Sure, Hailey, then 6, wasn't one to sit quietly at home with a book. But her teacher's suspicion that she might have a real problem like attention-deficit-hyperactivity disorder seemed far-fetched to this mother of six.
So Mejias sat in on Hailey's first-grade class.
"The 19 other children in the class could sit there and listen to a story," Mejias said. "Hailey was the only one who was up and walking around. It was very disruptive."
For some children, starting school is more than just making new friends and breaking in a new backpack. It can also be the time when the parents hear for the first time that their rambunctious or easily distracted child may have ADHD.
Attention-deficit-hyperactivity disorder is considered the third-most-common disability in U.S. children, according to government data. According to the National Institute of Mental Health, ADHD affects 3 percent to 5 percent of school-age children, and is more common in boys than girls.
Those with classic symptoms have a tough time sitting still. They may speak and act on impulse without considering consequences. They get bored quickly, are easily distracted and often can't follow instructions, let alone complete tasks.
While any child fidgets and doesn't pay attention from time to time, children with ADHD have symptoms for at least six months that are so severe that they disrupt family and school life.
Symptoms in some children appear by age 3 or 4, though ADHD often isn't formally diagnosed until elementary school, when the signs -- as in Hailey's case -- become obvious.
"In the early grades, such as preschool and kindergarten, there's a lot of playtime and a child's behavior may not stand out," said Tracey Kaly, a licensed mental-health counselor and clinical manager of BayCare Behavioral Health in New Port Richey, Fla. "But by third or fourth grade, where you have to sit in your seat for long periods and sustain long periods of focused attention and the classroom environment demands better behavior, it becomes more noticeable."
ADHD doesn't always mean hyperactivity. Girls, in particular, may simply be inattentive or daydream and can't focus attention on a task. In such cases, the condition might not be as obvious and may be diagnosed later in life or not at all. "Hyperactivity really stands out in childhood," said Kaly. "But the inability to be attentive may not be noticed until college or even later, such as in the workplace."
Elementary-school teachers are often the first to bring the disorder to a parent's attention. But it can take a drop in grades before some parents seek treatment for their child.
"Ninety percent of the time it's academic problems that bring families to us," said Dr. Michael Bengtson, an associate professor and chief of adolescent and child psychiatry at University of South Florida Health, based in Tampa.
Mejias took Hailey to see Bengtson after observing her in class. Talking with teachers, she realized that Hailey's older sister, Gabrielle, also exhibited symptoms, and she, too, was evaluated.
The process of diagnosing ADHD generally begins with a visit to the child's pediatrician to rule out other possibilities for the behavior, such as vision or hearing problems, learning disabilities, sleep disorders, depression or anxiety. Teachers and parents are asked to report their observations about the child's behavior, social interactions and academic performance. The diagnosis is usually made using guidelines from the American Psychiatric Association.
Although some parents may think teachers seeking classroom calm are too quick to blame ADHD, Bengtson said this is not the case, especially with classroom veterans.
"Experienced teachers -- the ones who have been teaching elementary school for 10, 15 years -- they know when a child has ADHD. They are darn good at recognizing it in children," he said.
It's not known what causes ADHD. Some experts say its roots may be genetic, or that exposure to tobacco, alcohol or other toxins during pregnancy may be to blame.
The trouble may be in the child's environment, such as exposure to lead in paint or plumbing fixtures in old buildings. Refined sugars and food additives also get some blame -- although there are plenty of children with poor diets who don't have ADHD.
Parents concerned about their children's ability to keep up in an increasingly competitive world might be more prone to seek help.
And a combination of some or all of these biological and social factors also could be at play.
While there is no cure, symptoms can be managed, usually with a combination of prescription medication and behavioral therapy, which often includes life skills such as learning to focus and organize.
Stimulant medication has a paradoxically calming effect on children with ADHD, and is the most common treatment. But there are more than a dozen Food and Drug Administration-approved drugs to treat ADHD in children age 3 and older, and not all are stimulants.
Many parents don't like the idea of giving their young child an amphetamine, which is what the stimulants are, for what may be perceived as behavior problems.
Mejias and her husband, who live in Land O'Lakes, weren't in favor of medications at first. But after doing extensive research and talking with teachers and other experts, they decided to try medication and behavior therapy. Gabrielle responded well to nonstimulant medication; Hailey, after much trial and error, had success with a stimulant. It's common for kids to go on and off medication on weekends, over summer vacation or after high-school graduation.
Some parents try behavioral therapy without medication first, though the most recent research shows that medication together with behavioral therapy offers the best results. Measures such as elimination diets and megadoses of vitamins haven't shown promise in studies.
As they are for all children, proper nutrition, activity and adequate sleep are key to healthy development, but lifestyle changes alone generally aren't enough to address ADHD.
Not treating ADHD can have long-lasting consequences. Some children fall behind in school, or have trouble making friends. Later in life, this failure to connect can translate into trouble getting and keeping jobs.
As they reach their teens, children whose untreated ADHD leads them to act impulsively are particularly at risk, Bengtson said. Some are more likely to experiment with drugs and alcohol. According to the American Academy of Child and Adolescent Psychiatry, teens with ADHD have nearly four times as many car accidents as those without the condition.
"YouTube is full of ADHD failures," said Bengtson, noting that numerous teens have made videos of dangerous stunts and put them online.
Can you outgrow ADHD?
Like much else with ADHD, the answer isn't cut and dried. The American Academy of Pediatrics says ADHD continues into adulthood in most cases, and the National Institutes of Health estimates that 4.4 percent of U.S. adults have the condition.
But Bengtson says that, in his experience, about two-thirds of his young patients outgrow the condition by their early to late 20s. And some people don't learn they have ADHD until adulthood -- some after their own children are diagnosed and the parents recognize familiar behavior patterns.
That's what happened with Ellen Mejias. After her daughters began therapy, she mentioned to Bengtson her frustration at not meeting her own high standards. Thinking back to her own childhood, she said, "I did have trouble in school and wasn't able to focus on what teachers were saying. My mind would wander off. I found myself daydreaming.''
She tried a prescription stimulant, Adderall. "I noticed a big change. I was able to sit down, straighten out my desk, get things in order and that made me feel better.'
Research shows that ADHD often runs in families -- Hailey and Gabrielle are biological sisters who were adopted by Mejias and her husband. Although she could not have passed it along to them genetically, it took seeing the girls' symptoms for Mejias to recognize similar signs in her own behavior.
As Mejias found, medication seems to help adult patients in particular with time management. Some who once had to always work late to get everything done find that, with better focus, they can put in shorter days at the office.
At any age, ADHD is a challenge. Most children with the condition need support and patience from parents, caregivers and at school. For instance, some kids may need to take tests in private so they can focus. They may need one-on-one help with homework and a quiet, orderly place to study.
Mejias sits with her girls, who are fourth- and fifth-graders, and goes through homework one question at a time. She also must repeat instructions and reminders about tasks.
Adults with ADHD may need to work on their own or with a therapist to improve their listening and organization skills.
"They must be motivated to reduce their symptoms and change their behaviors," Kaly said. "That's a key predictor of treatment success in adults."