Table 1

Clinical symptoms, neurocognitive testing findings and brain imaging findings in attention-deficit/hyperactivity disorder (ADHD)

Clinical symptoms2
Inattention (note: only five or more symptoms from this category required in individuals aged ≥17 years)Hyperactivity and impulsivity
  •  Often fails to give close attention to details or makes careless mistakes

  •  Often has difficulty sustaining attention in tasks or play

  •  Often does not listen when spoken to directly

  •  Often cannot follow through on instruction and fails to finish schoolwork, chores or workplace duties

  •  Often has difficulty organising tasks and activities

  •  Often has difficulty engaging in tasks that require sustained mental effort

  •  Often loses things

  •  Often easily distracted by extraneous stimuli (in older adolescents and adults, by unrelated thoughts)

  •  Often forgetful in daily activities

  •  Often fidgets 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 inappropriate

  •  Often unable to play or engage in leisure activities quietly

  •  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 difficulty waiting for their turn

  •  Often interrupts or intrudes on others

Neurocognitive testing findings supportive of a diagnosis of ADHD1 8
AttentionErrors of omissions and commissions
MemoryDecreased function in verbal/visual memory
MotorDecreased function in visual motor and reaction time
OthersDecreased function in working memory, set shifting, response inhibition, intelligence, achievement and planning/organisation
Brain imaging findings (research findings but not used for diagnostic purposes)
Anatomic MRI81
  •  Decreased volume in basal ganglia, cerebellum, frontal, parietal and occipital lobe

  •  Delayed maturation of cortex (delayed rate of cortical thinning)

Functional MRI (fMRI)
  •  Decreased activity within frontobasal ganglia network, occipital, parietal and temporal areas in response to motor response, interference inhibition and switching task

  •  Decreased activity within frontoparietal area in response to working memory task

  •  Decreased synchrony between anterior and posterior parts of default mode network (DMN) (resting-state fMRI)

  •  Reduced anticorrelations between DMN and attention network