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Developmental Disorders


The term "developmental disorder" or "developmental disability" means a severe, chronic disability of an individual that:

  • is attributable to a mental or physical impairment, or combination of mental and physical impairment
  • is manifested before the individual attains the age of 22
  • is likely to continue indefinitely
  • results in substantial functional limitations in three or more of the following areas of major life activity:
    • self-care
    • receptive and expressive language
    • learning
    • mobility
    • self-direction
    • capacity for independent living
    • economic self-sufficiency
    • reflects the individual's need for a combination and sequence of special, interdisciplinary, or generic services, individualized support or other forms of assistance that are of lifelong or of extended duration and are individually planned and coordinated.

*As defined by the Developmental Disabilities Assistance and Bill of Rights Act of 2000, Public Law 106-402.

Developmental Delay

Developmental delay is defined as failure to meet expected developmental milestones in one or more of the following areas: physical, social, emotional, intellectual, speech and language and/or adaptive development (sometimes called self-help skills, which include dressing, toileting, feeding, etc).

These delays are diagnosed when a child performs approximately 25 to 30 percent below age norms in one or more of these areas (with adjustment for prematurity in affected children). Progress occurs at a slower than expected rate following the anticipated sequence. Various medical and environmental causes exist.

Some examples of physical or mental disorders likely to result in delayed development are:

  • Chromosomal abnormalities
  • Genetic or congenital disorders
  • Severe sensory impairments, including hearing and vision
  • Inborn errors of metabolism
  • Disorders reflecting disturbance of the development of the nervous system
  • Congenital infections
  • Disorders secondary to exposure to toxic substances, including fetal alcohol syndrome.

The verification of delay is obtained through an evaluation process, which includes at least three of the following: informed clinical opinion to include observational assessment, standardized development test(s), developmental inventory, behavioral checklist, adaptive behavior measure and parent interview. Developmental delay can occur temporarily, or it can be long-term and never fully resolve.

Examples, Subsets and Synonyms for Developmental Delay:

  • Language Delay
  • Motor Delay
  • Global Delay

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