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What is attention deficit hyperactivity disorder (ADHD)?

ADHD is a neurodevelopmental disorder, meaning a condition that is due to differences in in the development and function of the nervous system. People with ADHD have trouble paying attention and controlling their impulses.

ADHD is the most common neurodevelopmental disorder in childhood, affecting an estimated 5 to 7 percent of all school-age children. ADHD usually develops before age 7, though sometimes symptoms are not noticeable until a child is somewhat older and encounters more challenging academic and social situations.

Children with ADHD are at particular risk for:

Adults who had ADHD as children are at much higher risk for a variety of mental health challenges, as well as challenges that may affect important life outcomes such as education, employment, and relationships. For these reasons, early diagnosis and intervention are very important.

Types of ADHD

ADHD can present in three different ways over the course of a child’s life:

  • Predominantly inattentive: Children with this presentation of ADHD have trouble paying attention, especially when they are supposed to focus on one thing for a sustained period, such as a classroom lesson or homework.
  • Predominantly hyperactive/impulsive: Children presenting with this type of ADHD (most commonly young boys) are often impulsive and have trouble sitting still. They may fidget, talk a lot, grab things out of other people’s hands, and interrupt. They are often impatient and suffer more injuries than other children as a result of their impulsive behavior. Hyperactivity tends to decrease with age, while impulsivity and inattention can persist into adulthood.
  • Combined: A child with this presentation of ADHD suffers from both impulsive and hyperactive behaviors, as well as inattention and distractibility. This is the most common presentation for children with ADHD.

Some children with ADHD may be able to function relatively well with minimal treatment, while others may need more extensive care to manage their symptoms.

Boys are approximately three times more likely to have ADHD. Young boys tend to show signs of hyperactivity, and as a result, they tend to be identified sooner than girls with ADHD.

Girls with ADHD are more likely to be inattentive and distracted. Because this form of ADHD is less disruptive, many are not identified and treated until much later, in middle or high school.

Answers Through ADHD Research

Answers Through ADHD Research is a series that discusses ADHD-related research and the implications for day-to-day care of children with ADHD.

Attention Deficit and Hyperactivity Disorder (ADHD) | Symptoms & Causes

What are the symptoms of ADHD?

Symptoms of attention deficit and hyperactivity disorder (ADHD) fall into three categories:


  • short attention span for their age
  • frequent careless mistakes
  • trouble listening or following instructions
  • trouble organizing activities
  • losing or forgetting things repeatedly and often
  • easily distracted
  • forgetfulness and poor study skills for their age


  • habit of interrupting others
  • difficulty waiting for their turn in school and with friends
  • tendency to blurt out answers instead of waiting to be called on
  • inclination to risky behaviors, often without thinking first


  • constant need to run or climb, often with no apparent destination
  • fidgeting or squirming when forced to sit still
  • excessive talking
  • difficulty engaging in quiet activities
  • shifting from one task to another without finishing any of them

What causes ADHD?

While researchers have not been able to identify a single cause, many studies indicate that ADHD runs in families. Other possible risk factors under investigation include:

Despite what some people think, there is no evidence that eating too much sugar, consuming certain food additives, watching too much TV, or growing up in a chaotic home environment cause ADHD.

Attention Deficit and Hyperactivity Disorder (ADHD) | Diagnosis & Treatments

How is ADHD diagnosed?

There is no single test to determine if a child has ADHD. Because the symptoms are similar for several other conditions, including anxiety disorders, depression, and certain learning disabilities, doctors usually conduct a series of physical, neurological, and psychological tests to rule out these other conditions. Criteria established by the American Psychiatric Association helps doctors determine if a child has ADHD. Psychological testing is also often needed to identify the conditions that frequently occur along with ADHD, such as learning disorders or other mental health disorders.

How is ADHD treated?

Treatment for ADHD includes three major components:

  • behavior therapy
  • medication
  • educational intervention

For many children, the most effective approach combines aspects of all three types of treatment, although for children younger than 6 years old, specialists in ADHD recommend that families start with behavior therapy first and introduce medication later

Behavior therapy

Behavior therapy helps both children with ADHD and their parents. Not only can it help all members of a family develop effective coping methods and ways to channel excess energy, it can also strengthen family bonds.

For parents, behavioral therapy is a way to learn strategies for responding to their children and reinforcing positive behaviors. The therapist will work with parents to identify and understand disruptive behaviors. Once parents learn what their children are getting out of problem behavior (usually attention or escape from activities they don’t like), they can then teach their children to substitute more effective ways to interact with others, express their emotions, and get their needs met. As children get older, they can start to take ownership of this process and recognize (and change) their own behavior patterns.


Two types of medication can be used to treat ADHD: stimulants and non-stimulants.

  • Stimulant medications have proven effective in improving the basic symptoms of ADHD — including inattention, impulsivity, and hyperactivity. Doctors believe stimulant medications increase dopamine in the brain, a chemical that occurs naturally in the body and supports focus and attention. Stimulants can have side effects, including trouble getting to sleep, decreased appetite, headaches, and jitteriness. Most side effects are mild and decrease with regular use.
  • Non-stimulants are available for children who cannot tolerate stimulant medications. Non-stimulants take longer to work than stimulants but can be effective in reducing impulsivity and increasing focus.

An important note: Children with any type of heart problem should always be examined and cleared by a cardiologist before beginning any new medication.

Educational intervention

Classrooms that require prolonged periods of sitting still and listening to a teacher can be especially challenging for a child with ADHD. Certain strategies in the classroom can help keep a child with ADHD engaged:

  • making sure class assignments are clear
  • assigning shorter assignments that are challenging but not discouraging
  • rewarding good impulse control; for instance, not interrupting
  • reducing distractions
  • providing opportunities for physical activity during the day
  • frequent communication between teachers and parents
  • allowing extra time to complete work
  • providing a variety of interesting approaches to learning

How we care for ADHD

The clinicians at the Boston Children’s Division of Developmental Medicine have years of experience assessing and providing ongoing, comprehensive treatment for children and adolescents with ADHD, including medication, behavioral therapy, and parent education and support. Our experts also work with parents and teachers to help them better understand the condition and develop strategies for interacting with children with ADHD most effectively.

Attention Deficit and Hyperactivity Disorder (ADHD) | Programs & Services