What are developmental disabilities?

Introduction

The concept of developmental disabilities was first introduced in the Developmental Disabilities Services and Facilities Construction Act of 1970. Subsequently, the Developmental Disabilities Assistance and Bill of Rights Act of 1990 defined developmental disabilities. The term “developmental disability” means a severe, chronic disability of a person five years of age or older that is attributable to a mental or physical impairment or a combination of both. The disability must manifest itself before the person reaches the age of twenty-two and be expected to continue indefinitely. It results in substantial functional limitations in three or more areas of major life activity, including self-care, receptive and expressive language, learning, mobility, self-direction, capacity for independent living, and economic self-sufficiency. The inclusion of the requirement of substantial functional limitations in three or more major life areas forms the basis for provision of services to individuals with severe impairments.

The American Psychiatric Association does not use the term “developmental disabilities.” However, it does identify pervasive developmental disorders (PDD) in its diagnostic manual. The description of these disorders and their manifestations in many ways overlaps the definition of developmental disabilities.

The terms “developmental disabilities” and “mental retardation” are often used as if they were synonymous. However, there are important distinctions as well as areas of overlap. The President’s Committee on Mental Retardation uses the definition developed and utilized by the American Association on Mental Retardation and generally understood by the Arc-USA (a national organization for people with mental retardation and related developmental disabilities and their families). Developmental disabilities covers more disabilities than those encompassed under mental retardation. Developmental disabilities indicate severe and chronic disabilities, while mental retardation includes a large number of individuals functioning at the mild level of cognitive impairment who require little or no support in adulthood. However, mental retardation does account for 70 percent of the people who are developmentally disabled. The term “medically fragile” is sometimes used to describe those vulnerable individuals whose complex medical needs can seriously compromise their health status.

Possible Causes

There are a multitude of etiologies for developmental disabilities. The cause can be prenatal, perinatal, or postnatal. Risk factors for developmental disabilities can be biological, environmental, or a combination of both. Genetics plays a role in conditions, such as Tay-Sachs disease and other inborn errors of metabolism, Klinefelter’s syndrome, Fragile X syndrome, and Down syndrome, that typically lead to developmental disability. Genetic causes may be chromosomal abnormalities, single gene defects, or multifactorial disorders. For example, autism appears to have a genetic component that interacts with developmental factors.

A number of conditions in the prenatal environment may increase the likelihood that a child will be born with the potential for a developmental disability. Fetal alcohol syndrome, for example, is completely preventable if pregnant women do not drink alcohol. Women who have sufficient amounts of folic acid in their diets reduce the risk of having a child with a neural tube defect that can result in a developmental disability.

Smoking during pregnancy, use of certain drugs such as cocaine or heroin, poor maternal nutrition, and extremes of maternal age greatly increase the chances of fetal brain damage or premature delivery and low birth weight. Babies with low birth weights are three times more likely than normal-weight babies to have developmental disabilities. Approximately 25 percent of very premature (twenty-seven weeks or earlier) infants have a severe developmental disability of some kind, according to Iris Lesser, director of the School-Age Unit at Yeshiva University's Children's Evaluation and Rehabilitation Center..

Children may later be at risk through environmental causes such as lead poisoning, inadequate nutrition, infections, nonstimulating environments, abuse, neglect, and traumatic brain injury.

Diagnosing Developmental Disabilities

Developmental disabilities are defined in terms of what an individual can or cannot do rather than in terms of a clinical diagnosis. They affect the typical processes in a child’s growth, particularly the maturation of the central nervous system. For this reason, early identification is important. The potential exists for an improved outcome if children are provided with education and habilitation. Prenatal diagnostic techniques may be appropriate for at-risk pregnancies. If a fetus is affected, the physician is better able to plan the delivery and prepare for special care during the newborn period.

Newborn screening is another way in which to identify conditions that can result in developmental disabilities if untreated. The Apgar test is administered by the medical staff in the delivery room at one minute, five minutes, and, if there are complications, at ten and fifteen minutes after birth. It measures the effects of various complications of labor and birth and determines the need for resuscitation. The test assesses physical responsiveness, development, and overall state of health using a scale of five items rated from 0 to 2. A low Apgar score at birth can signal the potential for a developmental disability.

Measurement of head circumference is a useful tool for predicting whether an infant is likely to have a neurodevelopmental impairment such as microcephaly. A blood test screening can be done for phenylketonuria (PKU), congenital hypothyroidism, galactosemia, maple syrup urine disease, homocystinuria, and biotinidase deficiency. Early detection of these conditions and appropriate intervention may reduce the severity of the resulting disability.

An older child can be referred to a developmental pediatrician for assessment of a developmental disability if the child has not attained expected age-appropriate developmental milestones, exhibits atypical development or behavior, or regresses to a previous level of development. Correcting for prematurity in developmental testing is necessary. An instrument commonly used is the Denver Developmental Screening Test. The more severely affected a child is, the clearer is the diagnosis, since an individual’s failure to meet developmental milestones may represent a short-term problem that resolves over time as the child “catches up.” Even readily identifiable indicators of potential disability do not always result in expected delays.

Related issues such as feeding, elimination, and cardiorespiratory problems; pressure sores; and infection control are also considered as part of the diagnosis. Screening for lead poisoning or psychological testing may be recommended.

At whatever age the person is referred, a multidisciplinary evaluation attempts to establish a baseline of the present level of performance, including both skills and deficits. Activities of daily living (ADLs) such as bathing, eating, and dressing are widely used in assessing this population. Needing assistance with ADLs becomes an important criterion for determining eligibility for public and private disability benefits. An appraisal is made of those deficits that can be remediated and those that require accommodation. The predictive accuracy of the diagnosis improves with the individual’s age.

Language development is another predictor variable. Individuals with developmental disabilities may have little or no apparent intent to communicate and may not understand that they can affect their environment through communication.

Though developmental disabilities by definition are severe, it is possible that a child not previously identified could be detected by routine public school prekindergarten screening.

The Developmentally Disabled Population

The Administration for Intellectual and Developmental Disabilities of the United States Department of Health and Human Services estimates that there are four million Americans with developmental disabilities. Data specific to the incidence and prevalence of developmental disabilities are difficult to obtain because of the various etiologies present in this population. Conditions that often fall under the umbrella of developmental disability include mental retardation, autism spectrum disorders, epilepsy, spinal cord injury, sensory impairment, traumatic brain injury, and cerebral palsy.

Though developmental disabilities can be associated with neurological damage, many of the conditions resulting in a developmental disability do not result in lowered intellectual functioning. Persons with developmental disabilities are estimated to comprise 1.2 to 1.3 percent of the population. This percentage has risen markedly since the mid-1970s for two reasons: increased life span for older individuals with disabilities and a greater number of children and adolescents surviving conditions that previously would have been fatal. The number of children ages six to seventeen classified as having an autism spectrum disorder in public special education program rose from 22,664 in 1994 to 211,610 in 2006.

Between 200,000 and 500,000 people in the United States over the age of sixty may have some form of developmental disability. Some of these individuals present special problems as they age. Those with epilepsy appear to be at greater risk for osteoporosis, while those with Down syndrome seem to begin the aging process earlier than others.

Treatment Options

The person with a developmental disability needs a combination of interdisciplinary services that are individually planned and coordinated and of lifelong or extended duration throughout the life cycle. Because the causes and manifestations of developmental disabilities are so varied, each affected person is unique and requires an individualized approach to treatment and training. Each disability has specific needs that must be addressed and accommodations that must be provided.

When a defect has been identified prenatally, fetal treatment may be possible to prevent developmental disability. Some inborn errors of metabolism respond to vitamin therapy given to the mother. Bone marrow transplants and fetal surgery have also been performed.

Services for children from birth to two years old provide special education as well as access to specialists in the areas of speech and physical therapy, psychology, medicine, and nursing. Assistive technology, physical adaptations, and case management are also offered. Medical management, monitoring, and consultation may be the responsibility of a developmental pediatrician.

Early intervention may be home-based, or the child can be enrolled in a center with a low child-to-teacher ratio. In either case, an Individual Family Service Plan (IFSP) is developed that includes a statement of the child’s present level of development; the family’s concerns, priorities, and resources; major outcomes to be achieved; the specific early intervention services to be provided; identification of the coordinator responsible for implementing the plan; and procedures for transition to preschool.

Among the equipment used in treating the child may be positioning devices, wheelchairs, special car restraints, amplification devices, and ambulation aids. Some children may require gastronomy tubes, tracheostomy tubes, cardiorespiratory monitors, nasogastric tubes, ventilators, bladder catheters, splints, or casting. They may be placed on antiepileptic medication, antispasticity drugs, antireflux medications, antibiotics, respiratory medications, or medications to influence mood and behavior.

The Individuals with Disabilities Education Act mandates comprehensive educational services for children from three through twenty-one years of age. Services are offered in a continuum of settings that are individually determined. These settings may include hospitals, residential facilities, separate day schools, homes, and public schools. Children are ideally placed in what the law refers to as “the least restrictive environment.” An Individualized Education Plan (IEP) replaces the IFSP.

ADLs are a prime focus of the educational program. The goal is to promote independence in such areas as eating, drinking, dressing, toileting, grooming, and tool use, which, in turn, fosters self-esteem.

Facilitating language acquisition
and communicative intent are critical to any intervention program. Many developmentally disabled individuals will need numerous stimulus presentations before acquiring a rudimentary vocabulary. For those children who continue to be nonverbal, alternative communication systems such as sign language, use of pictures, and communication boards are introduced to enable communicative interaction. Computers with interface devices such as switches or touch-sensitive screens may be introduced to children with cerebral palsy.

Children with developmental disabilities exhibit challenging behaviors more often than typically developing children. After previously unrecognized medical conditions are ruled out as causes, positive behavioral supports at home and in school or traditional behavior management programs aim at producing comprehensive change in those challenging behaviors. Drugs that affect central nervous system function can also be helpful in treating disruptive behaviors.

Newer treatment approaches include neurodevelopmental therapy and sensory integration therapy. Neurodevelopmental therapy is widely used by physical and occupational therapists. It emphasizes sensorimotor experience to facilitate normal movement and posture in young developmentally disabled children with cerebral palsy or other related disorders. Sensory integration is a normal process in which the child’s central nervous system organizes sensory feedback from the body and the environment and makes appropriate adaptive responses. Sensory integration therapy uses controlled sensory input to promote those adaptive responses.

Adults with developmental disabilities are living longer than ever before. Most have the ability to live happy, productive lives in their communities. One component of treatment is transition planning. The Developmental Disabilities Act of 1984 emphasizes the importance of employment of persons with developmental disabilities and offers guidelines for providing supported employment services. Other transition issues include sexuality, social integration, recreation, and community residential options. Medical and physical care plans are necessary since long-term consequences of therapeutic interventions may occur. Movement disorders can result from the prolonged use of neuroleptic medications, while bone demineralization may be secondary to the chronic use of certain anticonvulsants.

History of Treatment

Services for people now referred to as having a developmental disability began in the United States in 1848 in Boston. The philosophy of early schools was to cure the “deviant.” However, by 1877 a unidisciplinary medical model replaced the educational model and emphasized providing shelter and protection to this population. Later, the interest in Mendelian genetics led to a change in focus to protecting society from those whose disabilities were considered hereditary. By 1926, twenty-three states had laws requiring mandatory sterilization of the developmentally disabled on the books, and between 1925 and 1955 more than fifty thousand involuntary sterilizations occurred in the United States. In the 1950s, parents began to organize opportunities for individuals with developmental disabilities within public school systems.

Treatment evolved from the medical model to a multidisciplinary approach in which a physician consulted with members of other disciplines. Later, an interdisciplinary model emerged in which professionals from each discipline gathered together to discuss their individual assessments and decide jointly on a plan of care. More recently, a transdisciplinary approach has been developed in which professionals, along with the individual concerned and the family, work together equally to identify needs, plan care, implement interventions, and evaluate progress.

Though the term “developmental disabilities” was not used in it, PL 94-142, the Education for All Handicapped Children Act of 1975, mandated a free, appropriate, public education for children who could be considered developmentally disabled. The Education of the Handicapped Act Amendments of 1986 extended early identification and intervention services under the auspices of the public schools to identified children three to five years of age and those at risk for developmental disabilities. This legislation was reauthorized as the Individuals with Disabilities Education Act (IDEA) of 1990. Guarantees of equal protection under the law were extended to adults with developmental disabilities by the Americans with Disabilities Act (ADA) of 1990. In 2008, President George W. Bush signed the ADA Amendments Act, which expanded the ADA definition of disability, increasing the number of people covered under the act's provisions.

The years since 1970 have been a period of remarkable growth and achievement in services for individuals with developmental disabilities. Cultural, legal, medical, and technological advances have occurred. Services now include protection and advocacy systems under the auspices of state councils on developmental disabilities; university centers involved in education, research, and direct service; training in self-determination; and family supports. At the heart of this growth has been a transformation from a system of services provided primarily in institutions to one provided primarily in local communities. There has been a movement away from segregation and toward integration following what has been called the principle of normalization.

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