Table 2

Differential diagnosis of attention-deficit/hyperactivity disorder (ADHD)2 3 14

DiseaseShared featuresDifferences
Oppositional defiant disorder
Resisting work or school tasksDue to negativity, hostility and defiance (ODD)
Due to difficulty in sustaining mental effort, forgetting instruction and impulsivity (ADHD)
Intermittent explosive disorder (IED)High level of impulsive behaviourSerious aggression towards others; no attention problems (IED)
Less aggression; prominent attention problems (ADHD)
Autism Spectrum Disorder (ASD)Dysfunctional motor behavioursFixed and repetitive stereotypic movements (ASD)
Fidgetiness and restlessness (ADHD)
Specific learning disorder (LD)Learning problemsNot impaired outside of academic work (LD)
Due to inattention due to frustration or lack of interest (ADHD)
Intellectual disability (ID)Inappropriate and low intellectual ability in academic settingIn all other life activities (ID)
Not evident during non-academic tasks (ADHD)
ASDInattention, social dysfunction and behavioural outburstsDue to inability to tolerate a change from their expected course of events (ASD)
Due to impulsivity or poor self-control (ADHD)
Reactive attachment disorder (RAD)Social disinhibitionLack of enduring relationships; no full ADHD symptom cluster (RAD)
No lack of enduring relationships; full ADHD symptom cluster (ADHD)
Anxiety disorders (Anx)InattentionDue to worry and rumination (Anx)Due to attraction to external stimuli, including new or enjoyable activities (ADHD)
Depressive disorders
Inability to concentrateProminent only during depressive episode (Dep)
Always present (not episodic) (ADHD)
Bipolar disorder (BD)Increased activity, poor concentration and impulsivityAccompanied by elevated mood and grandiosity occurring in episodes that last a minimum of several days; rare in preadolescence (BD)
Significant mood change within same day (ADHD)
Personality disorders (PD)Disorganisation, social intrusiveness, emotional dysregulation and cognitive dysregulationOther clinical feature of borderline, narcissistic and other personality disorders (PD)
No fear of abandonment, self-injury or extreme ambivalence (ADHD)
Concussion (CC)Poor concentration, memory deficits and mood fluctuationDecline in neurocognitive testing after head injury compared with baseline (CC)
No change of neurocognitive function in tests (ADHD)