What is ADHD?

Attention Deficit Hyperactivity Disorder (ADHD), also referred to as Attention Deficit Disorder (ADD), is the most common neurodevelopmental condition affecting 3–5% of children and young people [1], which often persists into adulthood.

ADHD symptoms include poor attention, hyperactivity and impulsivity, yet, how these symptoms manifest and affect children, adolescents and adults can differ greatly. Importantly, various studies also highlight findings regarding gender differences and birthdate bias in ADHD, widening the scope beyond the common stereotype of the ‘naughty, hyperactive boy’ and calling for the identification of those who have been missed.

These factors, combined with the frequent presence of other conditions, including Autism Spectrum Disorder (ASD) – formerly known as Autism or Asperger’s – dysgraphia, dyspraxia and Oppositional Defiant Disorder (ODD), emphasize the need for a comprehensive clinical evaluation and diagnosis.

ADHD diagnosis

An ADHD diagnosis should only be made by a clinical psychologist, psychiatrist, pediatrician or other appropriately qualified healthcare professional. He or she will make a clinical decision following a comprehensive clinical evaluation, which can include, but is not limited to:

  1. Physical examination
  2. Clinical interviews
  3. Parent / teacher / self-reports by use of validated rating scales
  4. Objective ADHD test such as QbTest or QbCheck

Based on information gathered during a clinical comprehensive evaluation, a diagnosis is made when the child or adult’s ADHD symptoms meet the criteria as set out in a medical classification system such as the Diagnostic and Statistical Manual of Mental Disorders – 5th edition (DSM-5)*. The DSM-5 diagnostic criteria for ADHD are currently as follows:

“A persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development”

1. Inattention

Six or more symptoms of inattention for children up to age 16, or five or more for adolescents 17 and older and adults; symptoms of inattention have been present for at least 6 months, are inappropriate for developmental level, and negatively impact directly on social and academic/occupational activities. Symptoms are:

  • Often fails to give close attention to details or makes careless mistakes in schoolwork, at work, or with other activities.
  • Often has trouble holding 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 (e.g., loses focus, side-tracked).
    Often has trouble organizing tasks and activities.
  • Often avoids, dislikes, or is reluctant to do tasks that require mental effort over a long period of time (such as schoolwork or homework).
  • Often loses things necessary for tasks and activities (e.g. school materials, pencils, books, tools, wallets, keys, paperwork, eyeglasses, mobile telephones).
  • Is often easily distracted
  • Is often forgetful in daily activities.

2. Hyperactivity and Impulsivity

Six or more symptoms of hyperactivity-impulsivity for children up to age 16, or five or more for adolescents 17 and older and adults; symptoms of hyperactivity-impulsivity have been present for at least 6 months to an extent that is disruptive and inappropriate for the person’s developmental level and negatively impact directly on social and academic/occupational activities. Symptoms are:

  • Often fidgets with or taps hands or feet, or squirms in seat.
  • Often leaves seat in situations when remaining seated is expected.
  • Often runs about or climbs in situations where it is not appropriate (adolescents or adults may be limited to feeling restless).
  • Often unable to play or take part in leisure activities quietly.
  • Is often “on the go” acting as if “driven by a motor”.
  • Often talks excessively.
  • Often blurts out an answer before a question has been completed.
  • Often has trouble waiting his/her turn.
  • Often interrupts or intrudes on others (e.g., butts into conversations or games)

In addition, the following conditions must be met…

  • Several inattentive or hyperactive-impulsive symptoms were present before age 12 years.
  • Several symptoms are present in two or more setting, (such as at home, school or work; with friends or relatives; in other activities).
  • There is clear evidence that the symptoms interfere with, or reduce the quality of, social, school, or work functioning.
  • The symptoms are not better explained by another mental disorder (such as a mood disorder, anxiety disorder, dissociative disorder, or a personality disorder).
  • The symptoms do not happen only during the course of schizophrenia or another psychotic disorder.

Based on the types of symptoms, three kinds (presentations) of ADHD can occur…

Combined Presentation: if enough symptoms of both criteria inattention and hyperactivity-impulsivity were present for the past six months

Predominantly Inattentive Presentation: if enough symptoms of inattention, but not hyperactivity-impulsivity, were present for the past six months

Predominantly Hyperactive-Impulsive Presentation: if enough symptoms of hyperactivity-impulsivity, but not inattention, were present for the past six months.


*Please note: In Europe, the International Classification of Mental and Behavioural Disorders 10th revision (ICD-10) may be used as medical classification system, which includes different diagnostic terminology and criteria to the DSM-5.

[1]NICE. Attention deficit hyperactivity disorder: diagnosis and management of ADHD in children, young people and adults. Clinical Guideline 72. London: National Institute for Health and Clinical Excellence, 2008.