Onset of the disorder is no later than the age of 7 years.
The criteria should be met for more than a single situation, for example, the combination of inattention and hyperactivity should be present both at home and at school, or at both school and another setting where children are observed, such as a clinic. (Evidence for cross-situationality will ordinarily require information from more than one source; parental reports about classroom behaviour, for instance, are unlikely to be sufficient.)
The symptoms in A and C cause clinically significant distress or impairment in social, academic or occupational functioning.
A. At least six symptoms of attention have persisted for at least 6 months, to a degree that is maladaptive and inconsistent with the developmental level of the child.
Often fails to give close attention to details, or makes careless errors in school work, work or other activities
Often fails to sustain attention in tasks or play activities
Often appears not to listen to what is being said to him or her
Often fails to follow through on instructions or to finish school work, chores or duties in the workplace (not because of oppositional behaviour or failure to understand instructions)
Is often impaired in organising tasks and activities
Often avoids or strongly dislikes tasks, such as homework, that require sustained mental effort
Often loses things necessary for certain tasks and activities, such as school assignments, pencils, books, toys or tools
Is often easily distracted by external stimuli Is often forgetful in the course of daily activities
B. At least three symptoms of hyperactivity have persisted for at least 6 months, to a degree that is maladaptive and inconsistent with the developmental level of the child.
Often fidgets with hands or feet or squirms on seat
Often leaves seat in classroom or in other situations in which remaining seated is expected
Often runs about or climbs excessively in situations in which it is inappropriate (in adolescents or adults, only feelings of restlessness may be present)
Is often unduly noisy in playing or has difficulty in engaging quietly in leisure activities
Often exhibits a persistent pattern of excessive motor activity that is not substantially modified by social context or demands
C. At least one of the following symptoms of impulsivity has persisted for at least 6 months, to a degree that is maladaptive and inconsistent with the developmental level of the child.
Often blurts out answers before questions have been completed
Often fails to wait in lines or await turns in games or group situations
Often interrupts or intrudes on others (for example, butts into others’ conversations or games)
Often talks excessively without appropriate response to social constraints
National Collaborating Centre for Mental Health, National Institute for Health and Clinical Excellence. Attention deficit hyperactivity disorder: diagnosis and management of ADHD in children, young people and adults. British Psychological Society.