What are the key diagnostic criteria for ADHD in children and adults a

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

For children and young people, a diagnosis of ADHD requires:

Symptoms of hyperactivity/impulsivity and/or inattention that meet the diagnostic criteria in DSM‑5 or ICD‑11, and
Symptoms causing at least moderate psychological, social, educational, or occupational impairment based on interview and/or direct observation in multiple settings, and
The symptoms to be pervasive, occurring in two or more important settings such as social, familial, educational, or occupational environments. An assessment of needs, coexisting conditions, social, familial, educational or occupational circumstances, and physical health should be included. For children and young people, an assessment of their parents' or carers' mental health is also recommended.

For adults, a diagnosis should be made by a specialist and requires:

Evidence that symptoms of hyperactivity/impulsivity and/or inattention began during childhood and have persisted throughout life, and
Symptoms are not explained by other psychiatric diagnoses, and
The symptoms are associated with moderate or severe psychological, social, educational, or occupational impairment.

Additional criteria include:

Diagnosis should only be made by a healthcare professional with training and expertise in ADHD, based on a full clinical and psychosocial assessment, including developmental and psychiatric history, observer reports, and mental state assessment. Rating scales and observations are adjuncts but not sole basis for diagnosis.

What are the key diagnostic criteria for ADHD in children and adults according to NICE guidelines?