Attention Deficit Hyperactivity Disorder (ADHD)

Attention deficit hyperactivity disorder (ADHD) is a disorder that can cause hyperactive and impulsive behavior and/or make it difficult to pay attention. To be considered ADHD, these behaviors must last for at least six months and be present in two environments (home, work or school).

There are three types of ADHD:

  • Inattentive — classic ADD
  • Hyperactive — impulsive
  • Combined — the most common type

The cause of ADHD is unknown. It’s most likely caused by a chemical imbalance in the brain. There also appears to be a genetic factor since ADHD can run in families.


Watch Kim Penberthy, PhD, define and discuss ADD and ADHD. View behavior disorder transcript.

ADHD Risk Factors 

Factors that increase your chance of developing ADHD include:

  • Being a first-born boy
  • Having a parent or sibling (especially an identical twin) with ADHD
  • Having a mother who smoked cigarettes and/or drank alcohol during pregnancy
  • Having a parent with certain conditions, such as alcoholism or conversion disorder
  • Being born prematurely
  • Other possible risk factors, such as:
    • Head injury at a young age (less than two years old)
    • Being born with a serious heart condition
    • Having Turner syndrome 
    • Being exposed to certain pesticides
    • Spending over two hours a day watching TV or playing video games when young

ADHD Symptoms

Symptoms can vary according to the type of ADHD:


  • Easily distracted by sights and sounds
  • Doesn't pay attention to detail
  • Doesn't seem to listen when spoken to
  • Makes careless mistakes
  • Doesn't follow through on instructions or tasks
  • Avoids or dislikes activities that require longer periods of mental effort
  • Loses or forgets items necessary for tasks
  • Is forgetful in day-to-day activities


  • Restless, fidgets and squirms
  • Runs and climbs; not able to stay seated
  • Blurts out answers before hearing the entire question
  • Has difficulty playing quietly
  • Talks excessively
  • Interrupts others
  • Has difficulty waiting in line or waiting for a turn

Combined ADHD can present any of the symptoms of inattentive or hyperactive ADHD.

ADHD Treatment

Treatment aims to improve your ability to function.


Stimulants can help control behavior and increase attention span. They increase activity in parts of the brain that appear to be less active with ADHD. Some medications may have serious side effects, including heart and psychiatric problems, such as hearing voices and becoming manic. Your doctor will speak to you about any possible side effects. 

Behavior Therapy

Therapy sessions focus on practicing social and problem-solving skills. ADHD coaches work with individuals to help them organize and create strategies so that they can be more efficient and successful.

Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.