Section II: Introduction to Developmental Disabilities

In this section, we will discuss the definition of developmental disabilities, as well as some of the causes. While this information is important for a better understanding of the people you will support and will help you in your work, it is also important to understand the myths and misunderstandings which get in the way of people living meaningful lives in the community. We will also discuss how you can become a "roadblock remover" for people you support. 

The Definition of Developmental Disability

The term developmental disability (as defined by the Developmental Disabilities Act and adopted by the Virginia General Assembly) means a severe, chronic disability of an individual that is attributable to a mental or physical impairment or combination of mental or physical impairments that are manifested before the individual attains age 22 and are likely to continue indefinitely. Developmental disabilities result in substantial limitations in three or more of the following functional areas:

  • self-care
  • receptive and expressive language
  • learning
  • mobility
  • self-direction
  • capacity for independent living
  • capacity for economic self-sufficiency

An Intellectual Disability is a one type of Developmental Disability.

When we talk about developmental disabilities, we are talking about a variety of different conditions, which occur before individuals reach adulthood. For most developmental disabilities this age is 22, but for intellectual disability the age is before 18. The term intellectual disability (as defined by the American Association of Intellectual and Developmental Disabilities- AAIDD) means a person has significant limitations in intellectual functioning (reasoning, learning, problem solving) and in adaptive behavior, which covers a range of everyday social and practical skills. Thus disability originates before the age of 18. People with autism, cerebral palsy, and other mental or neurological conditions (seizures) are also considered to have a developmental disability. Other developmental disabilities may be strictly physical, such as blindness or deafness from birth or childhood. People with developmental disabilities may or may not also have an intellectual disability. Some developmental disabilities, such as Down syndrome, fetal alcohol syndrome and Fragile X syndrome, almost always occur with an intellectual disability.

Some Causes of Intellectual Disability

Some individuals have an intellectual disability that occurs from:

  • Genetics -something you are born with that is passed down by parents (e.g., Down syndrome, Fragile X).
  • Other physical causes (e.g., fetal alcohol syndrome, car accidents, shaken baby syndrome).
  • Social or environmental factors (e.g., lack of stimulation, trauma/abuse during the developmental years, lack of family and educational supports to promote mental development and adaptive skills).
  • Approximately 40% to 50% of individuals with an ID have no known cause of their disability.

Factors to Consider

On the basis of multiple evaluations, professionals can determine whether a person has an intellectual disability or other developmental disability and can make recommendations for supports for them.

In assessing and diagnosing disabilities, AAIDD stresses that professionals must take additional factors into account and consider things such as:

  • the typical environment of the person’s peers without disabilities;
  • language differences; and
  • cultural differences in the way people communicate, move, and behave.

 Assessments must also assume that:

  • everybody has strengths and weaknesses; and
  • people will become more independent if given the right supports, a chance to do things for themselves, and enough time to learn new skills.