Developmental Delays

dropping-the-term-crack-babies What Are Developmental Delays?1

Any discussion of students with developmental delays requires a clarification of terminology. The terms mental retardation and brain damage are still in common use, but they bring up stereotypic images of children who will never be able to function in “normal situations” because of behavioral idiosyncrasies or an inability to learn. Special educators and researchers know that this simply is not the case. Children with developmental delays can learn. However, they take much longer to grasp ideas or finish tasks.

Therefore, developmental delay (or, at least, developmental disability) is the term many educators prefer because it conveys the idea that children with such difficulties are worth the challenge of providing educational experiences that engage and encourage them. Nevertheless, use of this term to describe children with mental retardation is still controversial, and when the Individuals with Disabilities Education Act (IDEA) was reauthorized in 1997, its provisions allowed states and local education agencies to come up with their own definitions and eligibility criteria for this category.

Broadly speaking, people with developmental delays are those who develop at a rate significantly below average and who experience difficulties in learning and social adjustment. According to the Developmental Disabilities Act of October 2000, the current federal definition of developmental disability is as follows:

The term developmental disability means a severe, chronic disability in an individual five years of age or older that

1. Is attributable to a mental or physical impairment or a combination of mental and physical impairments
2. Is manifested before the person attains age 22
3. Is likely to continue indefinitely
4. 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

5. Reflects the individual’s need for a combination and sequence of special, interdisciplinary, or generic services, supports or other assistance that is of lifelong or extended duration and is individually planned and coordinated

In practice, consistently low scores on intelligence tests, in combination with poor academic functioning and a lack of adaptive skills, usually indicate that a child has a developmental delay. Delays in motor development and in receptive and expressive language skills are also typically present.

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Identifying Children with Developmental Delays

Children with developmental delays often are identified early in life, because they fall significantly behind their age-mates in meeting developmental “milestones.” For example, a young child may be slow to roll over, to understand his or her name, or to exhibit fine motor skills. Parents of infants often worry when their second child takes longer than the first to display a specific ability. In fact, the range of ages within which an infant should be able to perform any given skill is broad. Differences in personality can also result in variations in developmental progress. Nevertheless, special educators and medical doctors find that the behaviors and abilities of children who have developmental delays are well outside the age ranges for almost every developmental benchmark.

Identifying a child with a developmental delay involves going through a set of evaluative processes, including intelligence tests, developmental scales, adaptive behavior evaluations, and tests of general knowledge. Evaluation tools such as intelligence tests and behavioral scales are “normed” on a large sample of the population over a long period of time, and the scores from these sample assessments are distributed along a curve, offering a picture of how the measured attributes occur in the general population.

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Figure 4.1 illustrates a bell curve (or normal curve), the graphic shape that depicts scores on any standardized measure. On such a curve, the mean (average) score falls in the middle, and a statistical measure called a standard deviation is used to indicate the distance of a given score from the mean. When educational evaluators describe children with developmental delays, they are talking about children whose assessment scores fall at least two standard deviations below the mean. As you can see from the figure, this means that the children’s scores are lower than those of 95 percent of the population used to establish the norms for the test.


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Causes and Prevalence of Developmental Delays

The primary cause for developmental delays in school-aged children is genetic abnormalities. For example, phenylketonuria (PKU) is a single-gene disorder also referred to as an “inborn error of metabolism.” <MN4>PKU leads to mental retardation and other developmental delays if untreated in infancy because the body is unable to produce proteins or enzymes needed to convert certain toxic chemicals into nontoxic products or to transport substances from one place to another (Glanze, 1996). Infants with untreated PKU appear to develop typically for the first few months of life, but by twelve months of age most of them will have a significant developmental delay and will be diagnosed with mental retardation before they start school.

Down syndrome is an example of a chromosomal disorder. Chromosomal disorders happen sporadically and are caused by too many or too few chromosomes or by a change in structure of a chromosome. In the case of Down syndrome, the children have recognizable physical characteristics and limited intellectual endowment because of the presence of an extra chromosome 21.

Similarly, fragile X syndrome arises from a single gene located on the X (female) chromosome. It is the leading inherited cause of mental retardation.

Other causes of developmental delays include these:

  • Problems during pregnancy. Use of alcohol or drugs by a pregnant mother can cause mental retardation and developmental delays in the child. Research suggests that smoking also increases the risk of developmental delays. Other risks include malnutrition, certain environmental contaminants, and illnesses of the mother during pregnancy, such as toxoplasmosis, cytomegalovirus, rubella, and syphilis. Pregnant women who are infected with HIV may pass the virus to their child, leading to future neurological damage.
  • Problems at birth. Although any birth condition of unusual stress may injure the infant’s brain, prematurity and low birth weight predict serious problems more often than any other conditions.
  • Problems after birth. Childhood diseases such as whooping cough, chicken pox, measles, and HIB disease (which may lead to meningitis and encephalitis) can damage the brain, as can accidents such as a blow to the head or near drowning. Lead, mercury, and other environmental toxins can cause irreparable damage to the brain and nervous system. It is important to note that some children with developmental delays have problems caused by abuse or neglect. Although accidents and injuries can result in brain damage, it is often difficult to determine whether the child’s problems existed prior to the accident.

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Measured by both intelligence and adaptive behavior measures, approximately 1 percent of the general population has developmental delays. According to states’ data reported to the U.S. Department of Education, in the 1997–1998 school year approximately six hundred thousand students between the ages of six and twenty-one were classified as having developmental delays and received services from public schools. This figure does not include students reported as having multiple disabilities or those in noncategorical special education preschool programs.

Types of Developmental Delays

Development delays are disorders, not diseases, and should not be confused with mental illness. Many educators and researchers agree that people with developmental delays develop in the same way that people without a developmental disorder do, but at a slower rate. Others suggest that persons with developmental delays have difficulties in particular areas of basic thinking and learning such as attention, perception, or memory. Depending on the degree of impairment, individuals with developmental delays will follow different developmental pathways for academic, social, and vocational skills.

In an attempt to characterize and classify the varying degrees of difficulty these children experience, special educators often label children according to the type of services that they receive. In 1992, the American Association on Mental Retardation established a system of classification that is wide use extensively today. It includes the following four levels of intensity:

  1. Intermittent. Children who have developmental delays that do not cause day-to-day difficulties, but who need support occasionally and during transitions (for example, the transition from junior high to high school).
  2. Limited. Children who have daily limitations but can achieve a good degree of self-sufficiency after education and training.
  3. Extensive. Support for these children extends consistently throughout their lifetime, and they will not live independently.
  4. Pervasive. Used rarely, this term describes children whose developmental delays prohibit them from most self-help activities. These children typically require support for life-sustaining activities.


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The Roles of Specialists

When you teach children with developmental delays, they usually receive a variety of special services from therapists:

  • Occupational and physical therapy. Therapy can help children with motor skills (such as increasing range of motion and fine motor skills); perceptual skills (for instance, helping a child track an object in two- or three-dimensional space); and social-emotional skills (working in groups and taking turns). Occupational therapy also focuses on the use of adaptive and assistive technologies.
  • Speech/language therapy. This type of therapy can help children with articulation and expressive disorders; it also boosts receptive language skills.
  • Psychotherapy and psychiatric therapy. Broadly speaking, psychological therapy helps children with the process of recognizing, defining, and overcoming psychological and interpersonal difficulties. School psychologists are also responsible for administering many of the assessment inventories mentioned earlier. Psychiatrists have medical credentials and are responsible for managing any medication therapy the child may receive for psychological issues, such as anxiety, depression, and sleep disorders.

Collaboration with these specialists is extremely important. Teamwork and communication ensure that the adults working to help a child are pursuing related or compatible goals; that they can support, inform, and inspire each other; and that problems or obstacles are identified as early as possible. Occupational therapists, for example, can often contribute creative and useful strategies for helping children with developmental delays become ready to use technology, as well as suggestions for appropriate technologies and programs.

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Educational, Social, and Life-Skills Needs of Developmentally Delayed Students

In your study of children with developmental delays, take time to review some of the well-known theories of normal child development, such as those by Jean Piaget and Erik Erikson. (See Resources for Further Investigation at the end of this chapter.) Note, however, that children with developmental delays will not necessarily follow the same sequence of development as typical children. As a teacher, you may encounter a child with a developmental delay who has older-child cognitive skills such as conservation of quantity and some deductive reasoning, but, like a younger child, is still egocentric, with a limited capacity to shift perspective in order to understand or solve a problem. Some of these differences may be caused by environmental influences, because children with developmental delays are more likely than others to be in specially structured environments that in and of themselves affect the course of development.

Despite their differences, students with developmental delays have needs similar to those of other students. They are less likely, however, to take part in the regular curriculum than are children with learning disabilities or hearing or visual impairments. The challenge to the teacher is to provide materials that are developmentally appropriate and that offer opportunities to monitor small improvements or changes in performance.

Any teacher who works with children with developmental delays must balance the need for basic skills instruction with the children’s need to learn age-appropriate social and language skills. Materials for these students should be concrete and should emphasize practice targeted to the child’s developmental level and age level. Like seeking software for children with learning disabilities, finding applications that matched both chronological age and specific learning objectives can be difficult. Although a developmentally delayed student may be learning simple addition and subtraction skills at age eleven or twelve, he or she should not be using a software program designed primarily for prekindergarten or kindergarten students.

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