idd

IDD commonly refers to intellectual and developmental disabilities, a broad category of conditions characterized by limits in intellectual functioning and adaptive behavior with onset during the developmental period. In healthcare and social policy, IDD is used as an umbrella term that can encompass intellectual disability and related neurodevelopmental conditions. Key features include deficits in general mental ability and adaptive behavior, onset before age 18, and varying levels of support needs across education, employment, and independent living.

Causes are diverse and include genetic syndromes (such as Down syndrome), metabolic disorders, prenatal exposures, perinatal complications, environmental factors, and sometimes unknown etiologies. Prevalence estimates vary; commonly cited figures place intellectual disability at about 1% of the population, with higher rates when broader developmental conditions are included.

Diagnosis and services focus on functional impairment as well as cognitive ability. Assessments use standardized testing and adaptive-behavior scales, and a diagnosis reflects support needs across multiple life domains rather than IQ alone. Management emphasizes early intervention, inclusive education, skills development, and ongoing supports across childhood and adulthood. Person-centered planning, supported decision-making, and community-based services promote participation, independence, and equal rights.

In policy and practice, IDD terminology varies by country and context. Some regions use IDD as an umbrella term for individuals with intellectual disability and other neurodevelopmental disabilities, while clinicians distinguish between ID and related conditions in diagnostic manuals. Terminology and service provision continue to evolve toward greater inclusion and individualized supports.

Other uses: IDD can also stand for International Direct Dialing, the system that enables direct international telephone calls without operator assistance.