Intellectual disability assessment and classification — structured clinical viva

IQ alone? No. Diagnosis needs intellectual deficits and adaptive deficits and developmental onset. IQ about 2 SD below mean supports the intellectual criterion but is insufficient alone.[1][3][6]

Severity. Mild/moderate/severe/profound is based primarily on adaptive functioning and support intensity, not the IQ number alone. Use standardised adaptive scales plus real-world function across settings.[3][6]

Tests. Vision/hearing already important. First-tier genetics: chromosomal microarray and fragile X pathway; escalate to exome/genome when indicated (de Ligt landmark in severe ID). MRI/EEG/metabolic only for red flags.[1][2][4]

Tablet for intelligence? No medication treats core ID. Rare treatable metabolic causes are the exception once identified. Focus on education, therapies, communication supports and disability funding (e.g. NDIS).[1][6]

Age 18 / capacity. Plan transition early: adult disability and health services, education/employment, housing. Capacity is decision-specific with supported decision-making — the ID label does not equal global incapacity. Health surveillance matters because premature avoidable death is documented (CIPOLD).[5][6]

Name evidence. Moeschler/Shevell evaluation; Miller CMA; de Ligt exome; Tassé/Schalock adaptive-intellectual relation; Heslop CIPOLD; AAIDD supports framework overview.[1][2][3][4][5][6]