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Program: Individuals with intellectual and developmental disabilities
Population: Children and adults with a mental or physical impairment that is severe and chronic and that lasts a lifetime and results in substantial functional limitations
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SECTION 1: POPULATION AT RISK
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Child development is predictable, observable, and measurable. When a child misses developmental milestones, early intervention can mitigate a development delay and return the child to a normal development trajectory. Early intervention cannot ameliorate a developmental disability but can reduce the impact on daily function by stimulating adaptive skills, because the growing brain is highly responsive and capable of learning. (National Center on Birth Defects and Developmental Disabilities [NCBDDD], n.d.). Three terms commonly used are defined next. Only developmental disability is a legal term defined in federal law.
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Developmental disability (DD) is an umbrella term that describes functional impairment in physical, learning, language, or behavior including social and interpersonal skills (Zablotsky et al., 2019). Activities of daily living (ADL) are impacted as are instrumental activities of daily living (IADL) such as shopping, literacy, or numeracy. Causes include genetics, chromosomal anomaly (i.e., Down syndrome, fragile X syndrome), pregnancy complication (i.e., anoxia at critical fetal developmental stages or chemical assault such as fetal alcohol spectrum disorder), low birth weight, multiple births, prematurity, birth trauma, environmental factors (i.e., lead poisoning), metabolic conditions, and early childhood trauma (Cogswell et al., 2022; NCBDDD, n.d.). Other causes are not well understood for conditions such as autism spectrum disorder (ASD) and certain intellectual disabilities. Though some conditions are known at birth, other delays or disabilities are recognized only when milestones for daily tasks are not met (i.e., learning to crawl or speak in sentences; NCBDDD, n.d.; Zablotsky et al., 2019). Adult onset of intellectual and developmental disabilities can be caused by trauma, injury including alcohol or other drug use, environmental exposure to toxins, illness, or a disease condition like Alzheimer's (Kripke, 2019).
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Intellectual disability (ID) involves intellectual functioning or intelligence (IQ < 70) and includes the ability to learn, reason, problem-solve, adapt behavior, and develop social and life skills. It is diagnosed before age 18. Some medical diagnoses involve impaired intelligence (Purugganan, 2018).
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Intellectual/developmental disability (IDD) is used to describe conditions where individuals have compromised intelligence and functional impairment. Diagnosis requires a multidisciplinary assessment (Institute on Community Integration, n.d.). The term global developmental delay may be used for children under age 5 with significant delays in two or more developmental areas (Purugganan, 2018).
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Not all prebirth or birth traumas or developmental conditions affect cognition. For example, seizure disorder, low vision or blindness, hearing problem, cerebral palsy, spinal injury, attention deficit/hyperactivity disorder, or ASD may be present in highly intelligent individuals. However, all are related to the brain or nervous system and can co-occur and complicate the ...