What Is ADHD? - Symptoms & Treatment

Instructor: Diane Davis
People diagnosed with attention deficit hyperactivity disorder (ADHD) experience extreme energy, inattention, and sometimes a combination of both. They also struggle with focused activities. Explore the disorder in this lesson, and test your understanding with a quiz.


Attention deficit hyperactivity disorder (ADHD) is a mental health condition characterized by inattention, hyperactivity, and impulsivity. This common childhood disorder can continue into teenage and adult years. Children with ADHD typically have trouble staying focused and paying attention, difficulty controlling behavior, and exhibit hyperactivity (over-activity).

We have all seen that children can be inattentive, hyperactive, or impulsive sometimes, but what characterizes ADHD is the severity and continued occurrence of these behaviors. Before we can give an official diagnosis of ADHD, the child must exhibit symptoms, particularly in relation to their peers, for at least six months.


There are actually thought to be three different types of ADHD, each with different symptoms: predominantly hyperactive-impulsive, predominantly inattentive, and combined hyperactive-impulsive and inattentive. Diagnosing ADHD requires a comprehensive evaluation by a licensed health professional and cannot be done with one single test. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) lists diagnostic criteria in two categories:


  • Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
  • Often has trouble keeping attention on tasks or play activities.
  • Often does not seem to listen when spoken to directly.
  • Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).
  • Often has trouble organizing activities.
  • Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period of time (such as schoolwork or homework).
  • Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books, or tools).
  • Is often easily distracted by extraneous stimuli.
  • Is often forgetful in daily activities.

Hyperactivity and Impulsivity

  • Often fidgets with hands or feet or squirms in seat when sitting still is expected.
  • Often gets up from seat when remaining in seat is expected.
  • Often excessively runs about or climbs when and where it is not appropriate (adolescents or adults may feel very restless).
  • Often has trouble playing or doing leisure activities quietly.
  • Is often 'on the go' or often acts as if 'driven by a motor'.
  • Often talks excessively
  • Often blurts out answers before questions have been finished.
  • Often has trouble waiting one's turn.
  • Often interrupts or intrudes on others (e.g., butts into conversations or games).

So, in order to make a diagnosis, a child must exhibit six or more characteristics for the past six months. To be diagnosed with the predominately inattentive type of ADHD, the child must have six or more characteristics from the inattentiveness category but not six or more in the hyperactivity and impulsivity category. Likewise, a predominantly hyperactive-impulsive child meets the criteria outlined in the hyperactivity and impulsivity category but not as many from the inattentive list. The combined diagnosis is for children who have six or more symptoms in both categories.

Children with the predominantly inattentive type of ADHD don't exhibit what you may think of as classic symptoms. They may not have behavioral or social problems. Instead, they may sit quietly, seeming to behave as expected, but their focus is elsewhere. This type of child may not be diagnosed with ADHD because it's harder for parents and teachers to notice the symptoms.


Although scientists have yet to determine the exact causes of ADHD, some studies have shown that genes may play a role in the disorder. Most likely, ADHD is caused by multiple factors in each child. Current researchers are studying things like environmental factors, brain injuries, nutrition, and social environment to see what effects, if any, they have on ADHD.

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