Attention-Deficit/Hyperactivity Disorder (ADHD)
Attention-Deficit/Hyperactivity Disorder (ADHD) is the most common behavior disorder diagnosed in children and teens. ADHD refers to a group of symptoms that begin in early childhood and can continue into adulthood, causing difficulties at home, at school, at work, and within the community if not recognized and treated.

Difference between ADHD and ADD?
ADHD (Attention-Deficit/Hyperactivity Disorder) is the term used in the current Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV-TR) diagnostic criteria. ADD (Attention Deficit Disorder) with or without hyperactivity is the older term from the DSM-III-R.

Three Subtypes / Types of Attention-Deficit/Hyperactivity Disorder

• Inattention. This is the most common symptom. In addition to having difficulty paying attention, people with this ADHD symptom often are unable to consistently focus, remember, and organize. They may be careless and have a hard time starting and completing tasks that are boring, repetitive, or challenging.
• Impulsiveness. People who frequently act before thinking may not make sound judgments or solve problems well. They may also have trouble developing and maintaining personal relationships. An adult may not keep the same job for long or spend money wisely.
• Hyperactivity. A hyperactive child may squirm, fidget, and climb or run when it is not appropriate. These children often have difficulty playing with others. They may talk a great deal and not be able to sit still for even a short time. Teenagers and adults who are hyperactive don't usually have the more obvious physical behaviors seen in children. Rather, they often feel restless and fidgety, and are not able to enjoy reading or other quiet activities.

Adult ADHD
Attention-deficit/hyperactivity disorder (ADHD) in an adult often goes unnoticed because the person may maintain relationships, stay organized, and hold a steady job. It is not unusual for a parent to discover he or she has ADHD when his or her child is diagnosed with the disorder. The key to the diagnosis of ADHD for an adult is the presence of symptoms before he or she was 7 years of age. 

Hyperactivity in adults is often seen as:

• Fidgeting. Typically they swing their legs, shift in their seats, or tap their fingers.
• Constant motion. They feel "revved up," on the go, and show little or no ability to relax until exhausted.
• An inability to relax. They have difficulty trying to relax or to do quiet activities, such as reading or watching television.

 Inattention in adults is often seen as:

• Difficulty completing tasks that they do not find interesting or easy. However, these adults may become obsessed with activities that are interesting and enjoyable.
• Difficulty maintaining relationships.
• Difficulty focusing their attention on conversations, reading materials, or jobs. They may frequently move from one job to another.
• Forgetfulness, misplacement, or loss of things.
• Distractibility.