Attention Deficit and Hyperactivity Disorder (ADHD)

What is attention deficit hyperactivity disorder (ADHD)?

Attention deficit hyperactivity disorder (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 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.

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.

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.