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What is ADHD?

ADHD is a neurodevelopmental disorder affecting both children and adults. It is described as a persistent or ongoing pattern of inattention and/or hyperactivity-impulsivity that gets in the way of daily life or typical development. Individuals with ADHD may also have difficulties with maintaining attention, executive function (or the brain’s ability to begin an activity, organize itself and manage tasks) and working memory.

The Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association (APA), is the guide that lays out the criteria to be used by doctors, mental health professionals and other qualified clinicians when making a diagnosis of ADHD. The most recent edition of the manual, the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), was released in 2013 and included changes to the definition of ADHD that affect how the disorder is diagnosed in children and in adults.


What about the diagnosis of ADHD has changed with the DSM-5?

  • Teen and adult ADHD: For many years, the diagnostic criteria for ADHD focused on children as being the ones diagnosed with the disorder. This meant that many teens and adults with symptoms of ADHD might not have been diagnosed, or they weren’t diagnosed because the DSM-IV required documenting symptoms before the age of 7. Adults and teens can now be diagnosed more easily because the DSM-5 raises the age of when symptoms should be documented. In diagnosing ADHD in adults and teens, clinicians now look back to middle childhood (age 12) and the teen years for the onset of symptoms, not all the way back to childhood (age 7). Additionally, the new criteria describe and give examples of how the disorder appears in adults and teens.


  • Symptom description: In the previous edition, DSM-IV TR, the three types of ADHD were referred to as subtypes. This has changed; subtypes are now referred to as “presentations." Because symptoms may change over time, a person can change presentations during their lifetime. This change better describes how the disorder affects an individual at different points of life.


  • Severity: When diagnosing ADHD, clinicians now need to specify whether a person has mild, moderate or severe ADHD. This is based on how many symptoms a person has and how difficult those symptoms make daily life.


  • Pervasive presentation: Several symptoms of ADHD now need to be present in more than one setting rather than just some symptoms in more than one setting.


What are the DSM-5 criteria for diagnosing ADHD?

As with any DSM-5 diagnoses, it is essential to first rule out other conditions that may be the true cause of the symptoms. Because everyone shows signs of these behaviors at one time or another, the guidelines for determining whether a person has ADHD are very specific. In children and teenagers, the symptoms must be more frequent or severe compared to other children the same age. In adults, the symptoms must affect the ability to function in daily life and persist from adolescence. In addition, the behaviors must create significant difficulty in at least two areas of life, such as home, social settings, school or work. Symptoms must be present for at least six months.

The DSM-5 identifies three presentations of ADHD, depending on the presence or absence of particular symptoms. To be diagnosed with ADHD, children must have six or more of the nine characteristics and older teens or adults must have at least five of the nine characteristics in either or both of the DSM-5 categories listed below.

ADHD - Predominantly Inattentive Presentation
  • Often fails to give close attention to details or makes careless mistakes in schoolwork, at work or during other activities
  • Often has difficulty sustaining attention in tasks or play activities
  • Often does not appear to listen when spoken to directly
  • Often does not follow through on instructions and fails to finish schoolwork, chores or duties in the workplace
  • Often has difficulty organizing tasks and activities
  • Often avoids, dislikes or is reluctant to complete tasks that require sustained mental effort
  • Often loses things necessary for tasks or activities
  • Is often easily distracted by extraneous stimuli
  • Is forgetful in daily activities

ADHD - Predominantly Hyperactive/Impulsive Presentation
  • Fidgets with hands or feet or squirms in chair
  • Has difficulty remaining seated
  • Runs about or climbs excessively in children; extreme restlessness in adults. 
  • Difficulty engaging in activities quietly
  • Acts as if driven by a motor; adults will often feel internally as if they were driven by a motor
  • Talks excessively
  • Blurts out answers before questions have been completed
  • Difficulty waiting or taking turns
  • Interrupts or intrudes upon others

ADHD - Combined Presentation
  • Individual meets both sets of inattention and hyperactive/impulsive criteria


Do I need to diagnose the severity of symptoms?

As ADHD symptoms affect each person to varying degrees, the DSM-5 requires professionals who diagnose the condition to specify the severity of the disorder in the affected individual. Clinicians can designate the severity of ADHD presentation based on the DSM-5 criterion:

  • Mild: Few symptoms beyond the required number for diagnosis are present and symptoms result in minor impairment at home, school, work and/or social settings.
  • Moderate: Symptoms or impairment between "mild" and "severe" are present.


  • Severe: Many symptoms are present beyond the number needed to make a diagnosis, or multiple symptoms are particularly severe, or symptoms extremely impair an individual at home, school, work and/or social settings.

It is also important to note that the severity level and presentation of ADHD can change during a person's lifetime. This includes the possibility that ADHD can go in to partial remission. For this to happen, an individual who previously met all the criteria for a diagnosis would need to experience less than the original number of symptoms found to be present when they were first diagnosed, during the previous six month period.   



American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), Washington, D.C.: American Psychiatric Association.


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