Information on Five Challenging Disabilities-Intellectual Disability

We discuss how learning potential or intelligence is calculated based on ability scores relative to age expectations. The majority of classification systems consider an IQ below 70 to be within the ID range. Remember that approximately 2 percent of the population has an IQ score below 70. (You will see in Chapter Seven that 68 percent of the population has an IQ score between 85 and 115; the average IQ score is 100.)

REMEMBER: In order to establish eligibility for those functioning within the range of intellectual disability (ID), it is necessary to determine not only an IQ significantly below the average range, but also provide evidence of adaptive functioning deficits in at least two areas.

The Range of Intellectual Disability   The IQ scores of individuals who are classified as intellectually disabled can range from an IQ of about 70 (plus or minus 5 points of measurement error) to an IQ below 20. There is great variability in the characteristics of children whose scores fall within this wide range. Although the range is large, the vast majority (85 percent) of children with ID fall within the mild range (IQ range from 55 to 75). Children who fall in the lower ranges (IQ less than 40) often have multiple disabilities. IDEA 2004 does not specify different levels of ID, but the DSM-IV-TR (APA, 2000) provides four categories. The percentages of individuals who score in different ranges and the expectations associated with each of the levels of ID (mild, moderate, severe, and profound) are shown in Table 3.3.

Generally, intellectual disability refers to limitations in mental ability that may influence daily living and adaptation to the environment in several areas of functioning, such as daily living skills, communication skills, academic skills, social skills, self-help skills, health and safety, community use (leisure and recreation) and vocational potential.

Associated Characteristics   Children with ID often have trouble learning at the same rate and depth of understanding as their nondisabled peers. They may require many repetitions to acquire a concept and may be unable to grasp abstract concepts. Developmental milestones such as talking, crawling, sitting, walking, or toilet training may be delayed. Some children with ID have a specific syndrome, such as Down syndrome (caused by a chromosomal defect) or fetal alcohol syndrome (caused by maternal alcohol consumption during pregnancy). Children with ID due to specific syndromes often have associated physical characteristics (for example, poor muscle tone and slanted eyes associated with Down syndrome or a flattened nose and widely spaced eyes associated with fetal alcohol syndrome).

Educational Planning   A comprehensive psychological assessment is recommended to provide adequate insight into a child's strengths and weaknesses prior to determining special education eligibility and, if necessary, developing an IEP. Some children may require minimal accommodations in their educational program, while others may require educational programs that address significant concerns in behavioral, social, emotional, or adaptive areas.

In working with children with ID, it is important to break down goals into smaller steps in order to ensure understanding. It is also important to allow increased time for repetition and consolidation of skills. Parents and teachers can increase a child's chances of success by working together to provide a consistent home and school program that allows the child to generalize skills across different environments.