ADHD, or Attention-Deficit/Hyperactivity Disorder, is a neurodevelopmental disorder that affects behavior and attention. It is one of the most common mental disorders affecting children. ADHD is usually first diagnosed in childhood and often lasts into adulthood. There are three main types of ADHD:

• Predominantly inattentive presentation: This type of ADHD is characterized predominantly by inattention and distractibility without hyperactivity.
• Predominantly hyperactive/impulsive presentation: This type of ADHD is characterized predominantly by impulsive and hyperactive behaviors without inattention and distractibility.
• Combined presentation: This is the most common type of ADHD, characterized by impulsive and hyperactive behaviors as well as inattention and distractibility.

ADHD is not considered a learning disability, but research indicates that from 30-50 percent of children with ADHD also have a specific learning disability, and that the two conditions can interact to make learning extremely challenging. A diagnosis of ADHD is based on the presence of persistent symptoms that have occurred over a period of time and are noticeable over the past six months. While ADHD can be diagnosed at any age, this disorder begins in childhood.