Common Forms of Developmental Disabilities

Developmental disabilities refer to conditions which manifest themselves during childhood (before the age of 22 years). They typically consist of disorders which may alter or delay the normal development of one or more of the following skills; language, speech, learning, self-help, mobility, or independent living. Any disorder or condition which is chronic in nature and significantly alters normal human development falls under the heading of developmental disability. Although five of the most common forms of developmental disability are discussed here, remember that this list is in no way exhaustive.

Cerebral Palsy
Down Syndrome
Mental Retardation
Spina Bifida


Autism refers to a pervasive developmental syndrome characterized by a distinct group of behaviors and cognitive differences. It often is associated with genetic and acquired conditions that affect brain development. The etiology of autism is unclear. The complexity and spectrum of autistic function suggest diversity in causal relationships/factors. It has been posited that the brains of individuals with autism may demonstrate abnormal micro-architecture and/or disturbances in select neurotransmitter metabolism. There are many factors which influence the degree of expression of autism, such as co-morbidity of mental retardation and/or Fragile-X syndrome. Age also appears to be a determinant of autistic expression; symptoms often improve as a child develops language skills and thus gains some control of his or her environment. Symptoms of autistic expression are typically strongest between the ages of four to five years. It is estimated that autism affects approximately 1-2 persons per thousand, with males being affected approximately 3.5 times as frequently as females. Recent studies have indicated perhaps even a higher prevalence rate (as high as 1 in 250).

(See the DSM-IV-R for expanded diagnostic criteria.) www.msnusers.com/TheAutismHomePage/communicationsymptomsdsmiv.msnw

Persons with autism often display one or more of the following: impaired development of social skills; impaired development of verbal and nonverbal communication skills; ritualistic and perseverative behavior; resistance to environmental change or change in daily routines; gaps in intellectual development; poorly developed play skills; pronomial reversal; labile mood; and unusual responses to sensory experiences. Poor motor coordination may also be present, especially in individuals diagnosed with Asperger's Syndrome (an autistic spectrum disorder).
Healthcare providers should be aware that persons with autistic disorders may experience alterations in the processing of sensory stimulation. Sensations of touch, hearing, smell, and taste may be perceived very differently by a person with autism than others. An individual may demonstrate a higher tolerance for pain, yet at the same time experience "light" touch or loud sounds as painful or intolerable. Avoidance of tactile sensory stimulation may be quite significant in some individuals with autism-thus it may be necessary to modify examination procedures. It is also very important for providers to consider the potential for increased pain tolerance when conducting diagnostic evaluation of persons with autism.
Another important issue to consider when working with individuals having autistic disorders revolves around communication. Persons with autism frequently display differences in communication skills. Nonverbal communication may be used extensively, depending on the level of autistic expression and/or presence of mental retardation. It is important to understand that many seemingly unrelated behaviors may express communicative intent in individuals with autism. Several helpful strategies exist for relating to persons with autism. One strategy is to use pictorial scripts, such as social stories, which help explain to the patient what will happen during the examination. Another helpful strategy involves the demonstration of procedures on another person, typically a parent.

Huebner, R.A., and Dunn, W. (2001). Introduction and basic concepts. In Huebner, R.A., (Ed.), Autism: A sensorimotor approach to management (pp. 3-40). Gaithersburg, MD: Aspen Publishing, Inc.

For further information on autism see:
Autism Q&A from the National Institute of Child Health and Human Development (NICHD): www.nichd.nih.gov/publications/pubs/autism/QA/index.cfm


Cerebral Palsy

Cerebral Palsy is "an umbrella term for a group of non-progressive, but often changing, motor impairment syndromes secondary to lesions or anomalies of the brain arising in the early stages of its development" (Kuban and Leviton, 1994). Congenital cerebral palsy (90% of cases) may be caused by inadequate blood or oxygen supply to the unborn child, illness during pregnancy, premature birth, birth trauma, etc. Acquired cerebral palsy (10% of cases) may be caused in the first few months after birth by head trauma, infections (encephalitis, meningitis, herpes simplex, cytomegalovirus), exposure to toxic substances, severe malnutrition, child abuse, etc.

A wide variety of associated conditions may or may not exist for persons with cerebral palsy, but several of the most common include:

  • Seizure disorders
  • Vision impairment
  • Speech impairment
  • Hearing impairment
  • Scoliosis
  • Tonal problems
  • Bladder problems (urinary tract infection)
  • Excessive drooling
  • Poor nutrition
  • Depression
  • Joint contractures
  • Hip dislocation
  • Joint, muscle or other pain
  • Skin breakdown
  • Gastrointestinal problems (oral motor dysfunction, gastroesophageal reflux, esophagitis, gastritis, ulcers, constipation and bowel obstruction)
  • Pneumonia
  • Osteoporosis

Developmental disabilities: Resources for healthcare providers. (n.d.). Retrieved November 2002, from the Developmental Disabilities Health Information Network Web site: http://www.ddhealthinfo.org/ggrc/doc2.asp?ParentID=2850

Several things are of primary consideration when treating individuals with cerebral palsy. First is that while many individuals with cerebral palsy also have mental retardation, the majority do not. It is important to recognize that an individual may have normal, or above normal intelligence even if he or she is unable to speak or communicate that level of intelligence in a more conventional way. Second is that persons with cerebral palsy often have various levels of speech impairment and may use augmentative communication devices, nonverbal communication, slow or difficult to understand speech, or a combination thereof. Third, cerebral palsy is often accompanied by various levels of mobility impairment. The person may require the use of a wheelchair, braces or other adaptive equipment. Being aware of these considerations beforehand and preparing appropriately will lessen the chance for awkward or inaccessible office situations.

Both speech and mobility considerations will be elaborated upon later. Remaining cognizant of both the potential for and possible severity of speech and mobility impairment in persons with cerebral palsy will help the health care provider in addressing these issues.

For more information about cerebral palsy:

General reading:

Aging and cerebral palsy:


Kuban, K., & Leviton, A. (1994). Cerebral palsy. New England Journal of Medicine, 330(3), 188-195.


Down Syndrome

Down syndrome is caused by a chromosomal defect and is marked by certain distinctive physical characteristics as well as typically some level of intellectual disability. Current estimates place the prevalence of Down syndrome at 1 in 700 persons. Persons with Down syndrome are highly susceptible to a number of other medical conditions including hearing deficiency, congenital heart disease, thyroid problems, obesity, atlantoaxial instability and early onset of Alzheimer's disease. Persons with Down syndrome are also at higher risk for leukemia.

In addition to these considerations, persons with Down syndrome often have some level of communication impairment. Understanding and facilitating nonverbal communication may be necessary to effectively relate to persons with Down syndrome.

Because individuals with Down syndrome frequently have some level of intellectual disability, the physician must make every effort to assure that the patient fully understands the instructions being given to him or her. This may be less of an issue for a child who is accompanied by an adult. However, remembering to speak in terms that the person can easily understand (without being condescending) and verifying that the patient has understood any instructions are important considerations of which to be aware.

One idea to ensure that patients understand instructions is to write the instructions out for the patient and verbally go over them. Another idea is to arrange a follow up call to remind and make sure that the patient is following the instructions.

For more information about Down syndrome:
Health Care Guidelines for Individuals with Down Syndrome: http://www.denison.edu/dsq/health96.html

General Medical Overview: http://ddhealthinfo.org/ggrc/doc2.asp?ParentID=3168
National Association for Down Syndrome, http://www.nads.org
National Down Syndrome Society, 800-221-4602, http://www.ndss.org


Mental Retardation

Mental retardation is the most common developmental disability. The definition according to the American Association of Mental Retardation is "a disability characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills". This disability originates before age 18. The following five assumptions are essential to the application of this definition:

  1. Limitations in present functioning must be considered within the context of community environments typical of the individual's age peers and culture.
  2. Valid assessment considers cultural and linguistic diversity as well as differences in communication, sensory, motor and behavioral factors.
  3. Within an individual, limitations often coexist with strengths.
  4. An important purpose of describing limitations is to develop a profile of needed supports.
  5. With appropriate personalized supports over a sustained period, the life functioning of the person with mental retardation will generally improve." (p. 1)

(Source: Mental Retardation: Definitions, Classifications and Systems of Supports (2002). Washington: American Association of Mental Retardation)

The 2002 AAMR definition of mental retardation emphasizes the types and intensities of supports (e.g., personal, assistive technology, environmental) that a person needs to live a fulfilled and productive life in typical community settings (home, a job, friends, recreational activities, etc.). Unlike previous conceptions of mental retardation, which focused almost exclusively on deficits, limitations and all that a person cannot do, the 2002 definition emphasizes that the functional capabilities of all persons can improve with carefully designed, individualized supports, and that all people are capable of living in the community with the provision of such supports.

Want to know more general information about developmental disabilities? Administration for Children and Families: http://www.acf.dhhs.gov/programs/add/


Spina Bifida

Spina bifida is caused by the failure of the spine to close completely during the first month of pregnancy. Persons with spina bifida often experience paralysis, hydrocephalus, learning disabilities and swallowing problems.

Of the four major developmental disabilities discussed here, spina bifida is the least likely to affect such areas as speech and cognition (although some degree of learning disability is fairly common). Persons with spina bifida are likely to use wheelchairs or other ambulatory aids. As such, the accommodations needed to appropriately treat a patient with spina bifida will likely be physical in nature. See the section below on physical accommodations.

The nationwide prevalence of spina bifida is estimated to be approximately 1 in 2,000; however in Kentucky prevalence estimates are slightly higher due to dietary deficiencies in folic acid and hereditary factors.

General Medical Information about spina bifida: http://ddhealthinfo.org/ggrc/doc2.asp?ParentID=3173
Spina Bifida Association of America: http://www.sbaa.org/