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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.

What are the types of attention deficit hyperactivity disorder (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.

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?

  1. Genetics: ADHD is mostly caused by genetic factors. ADHD runs in families, and can be associated with common genetic differences, as well as with rare genetic changes that can be spontaneous (happening by chance during conception) or passed down through parents (inherited). Read more about what Boston Children’s researchers are learning about the genetics of ADHD here.
  2. Environmental risk factors: There are some risk factors in the infant or child’s environment that can cause ADHD or make ADHD symptoms worse. These include exposure to alcohol or tobacco during pregnancy, traumatic brain injury, low birth weight, premature delivery, and exposure to lead at an early age. 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, although some of these behaviors may temporarily worsen symptoms of ADHD in some children.

Read about what Boston Children’s researchers are learning about the genetics of ADHD.

ADHD | Diagnosis & Treatments

How is ADHD diagnosed?

There is no single test, like a blood test or computer test, that can accurately diagnose ADHD. ADHD in children is diagnosed through consideration of behavioral ratings that are provided by caregivers, teachers, and other adults who know the child well. Symptoms of inattention, hyperactivity, and/or impulsivity must cause functional impairment for the child (e.g., academic challenges; difficulties with peers). In many cases, ADHD can be diagnosed by a child’s primary care provider or pediatrician. In some cases, additional assessment by a specialist is necessary. This additional psychological or neuropsychological evaluation can help determine whether a child’s symptoms are due to ADHD or another disorder, like anxiety, depression, or learning disorders. Sometimes, a child has ADHD in addition to other psychiatric or learning disorders that need to be recognized and treated. During a psychological or neuropsychological evaluation, clinicians conduct a series of physical, neurological, and psychological tests to get a full picture of the child. Criteria established by the American Psychiatric Association help clinicians determine if a child meets diagnostic criteria for ADHD.

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 is an evidence-based treatment for children and teens with ADHD. Parents and teachers can use behavior management strategies to support children with ADHD at home and in the classroom.

Parent/caregiver training in behavior management (also called parent management training or behavioral parent training) is a form of behavior therapy that directly involves parents. Parents learn strategies that they independently use to increase the child’s positive behaviors while decreasing the child’s unwanted behaviors.

Cognitive-behavior therapy can be beneficial for adolescents and adults with ADHD to learn strategies for self-regulation and executive functioning, and it is recommended for children with co-occurring conditions such as anxiety and depression. For children/adolescents, individual therapy often includes parents as therapeutic allies.  


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 an alternative to 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.

ADHD | Resources for Patients & Families

Boston Children's ADHD guides

Web resources

Medication guides (AACAP)

ADHD | Programs & Services