You may have heard of ADHD as a joke about a jittery co-worker who's "hyper" or a forgetful friend "having ADD." You may have even heard talks about the debate over the number of kids who take Ritalin or other meds for ADHD. But exactly what is ADHD?

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A strict medical definition can help parents understand what their child is facing, and also differentiate between actual ADHD and a child (or adult) who is high-energy, impatient or has ADD without the "H," which is the hyperactive component.

According to the National Institute of Mental Health, a government organization, the initials ADHD stand for "attention-deficit/hyperactivity disorder, a brain disorder marked by an ongoing pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development."

  • Inattention is characterized by wandering off task. A person displaying inattention also "lacks persistence, has difficulty sustaining focus, and is disorganized," NIMH noted, "and these problems are not due to defiance or lack of comprehension."
  • Hyperactivity is identified as a person who seems to move about constantly, or excessively fidgets, taps, or talks, according to NIMH. "In adults, it may be extreme restlessness or wearing others out with constant activity."
  • Impulsivity involves a person making hasty actions in the moment without first thinking about them, especially if the actions are potentially harmful. Another characteristic of impulsivity is a desire for immediate rewards or an inability to delay gratification, NIMH said.

Who's at risk?

Even the NIMH, which is the leading federal agency for mental health research, admitted that scientists don't fully understand what causes ADHD. They have identified numerous factors that contribute to a child's odds of having ADHD, including the following:

  • Genes, meaning some aspects of ADHD may be attributed to inherited traits
  • A mother who smoked cigarettes, or used alcohol or certain drugs during pregnancy
  • A fetus' exposure to environmental toxins during pregnancy
  • Exposure to environmental toxins, such as high levels of lead, at a young age
  • Low birth weight
  • Brain injuries

NIMH also noted that ADHD is more common in males than females, while females with ADHD are more likely to have problems primarily with inattention.

Conditions common in people who have ADHD include learning disabilities, anxiety disorder, conduct disorder, depression and substance abuse.

How to tell if your child has ADHD

Most children who potentially have ADHD end up going for an evaluation shortly after they enter grade school, because that's when their inability to focus, follow directions and control behavior becomes a real barrier to success in a structured setting, according toParenting,com. But the age range for diagnosis can include kids as young as 4 and up to age 18.

Parenting listed symptoms from the American Psychiatric Association's Diagnostic and Statistical Manual IV, (DSM IV), the criteria a doctor would use to diagnose your child. It noted that for behaviors from the list to "be truly considered signs of ADHD, they must last for six months, be more severe than in other children the same age – i.e., they're causing significant problems at school, home and/or in social settings -- and some symptoms should have been present before your child turned 7."

To be diagnosed with ADHD/inattentive type, a child would have displayed at least six of these nine symptoms for at least six months:

  1. Does not pay close attention to details, makes careless mistakes
  2. Often has trouble keeping attention on tasks
  3. Often does not seem to listen when spoken to directly
  4. Often does not follow through on instructions and fails to finish work or chores (because of failure to understand, not defiance)
  5. Often has trouble organizing activities
  6. Often avoids or dislikes things that take a lot of mental effort for a long period of time.
  7. Often loses things needed for tasks and activities
  8. Is often easily distracted
  9. Is often forgetful in daily activities

To be diagnosed with ADHD/hyperactive-impulsive type, a child would have displayed at least six of these nine symptoms for at least six months::

  1. Often fidgets with hands and feet or squirms in seat
  2. Often gets up from seat
  3. Often excessively runs about or climbs when not appropriate
  4. Often has trouble playing or doing leisure activities quietly
  5. Is on the go as if driven by a motor
  6. Often talks excessively
  7. Often blurts out answers before questions have been finished
  8. Often has trouble waiting his turn
  9. Often interrupts or intrudes on others

Easing the ADHD situation 

Regardless of the way a child or adult developed ADHD, anyone with the diagnosis will require guidance and understanding from parents, families and teachers to reach their full potential and to succeed, according to the NIMH. "For school-age children, frustration, blame, and anger may have built up within a family before a child is diagnosed," it noted. "Parents and children may need special help to overcome negative feelings. Mental health professionals can educate parents about ADHD and how it affects a family. They also will help the child and his or her parents develop new skills, attitudes and ways of relating to each other."