Attention Deficit Hyperactivity Disorder (ADHD) is a condition that becomes apparent in some children in the preschool and early school years.

It is hard for these children to control their behavior and/or pay attention. It is estimated that between 3 and 5 percent of children have ADHD, or approximately 2 million children in the United States.

ADHD was first described by Dr. Heinrich Hoffman in 1845. 

Since then, several thousand scientific papers on the disorder have been published, providing information on its nature, course, causes, impairments, and treatments.

Symptoms

The principal characteristics of ADHD are inattention, hyperactivity, and impulsivity. These symptoms appear early in a child’s life.

Symptoms of ADHD will appear over the course of many months, often with the symptoms of impulsiveness and hyperactivity preceding those of inattention, which may not emerge for a year or more. Different symptoms may appear in different settings, depending on the demands the situation may pose for the child’s self-control.

 According to the most recent version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), there are three patterns of behavior that indicate ADHD.

• People with ADHD may show several signs of being consistently inattentive.
  
• They may have a pattern of being hyperactive and impulsive far more than others of their age.
  
• Or they may show all three types of behavior.
  

This means that there are three subtypes of ADHD recognized by professionals.

• These are the predominantly hyperactive-impulsive type (that does not show significant inattention);
• The predominantly inattentive type (that does not show significant hyperactive-impulsive behavior) sometimes called ADD—an outdated term for this entire disorder; and
  
• The combined type (that displays both inattentive and hyperactive-impulsive symptoms).