AHRC-NYC online/FAQs

A developmental disability is a disability that originates before the age of twenty-two and is expected to continue indefinitely. It is attributable to a condition such as mental retardation, or cerebral palsy, epilepsy, neurological impairment, autism or traumatic brain injury, when such conditions result in impairment of general intellectual functioning or adaptive behavior. Impairment of intellectual functioning means that a person has an intellectual quotient (an IQ as measured by a standardized IQ test ) which is two or more standard deviations below the mean (an IQ of 70 or less using a scale with a mean of 100 and a standard deviation of 15). Impairment of adaptive behavior means that the person has overall adaptive behavior which is significantly limited in two or more skill areas (communication, self-care, home living, social skills, community use, self direction, health and safety, functional academics, leisure and work). These limitations are a direct result of the person’s cognitive deficits.

A developmental delay is slowed or impaired development of a child who is under five years of age and who is at risk of manifesting a developmental disability because of the presence of one or more of the following: chromosomal conditions associated with mental retardation; congenital syndromes associated with delay in development; metabolic disorders; prenatal and perinatal infections and significant medical problems; low birth weight; postnatal acquired problems known to result in delays; or delays of 1.5 standard deviations or more in the area of communication, and/or self-help, and/or social emotional, and/or motor skills, and/or sensory development, and/or cognition.

AHRC recognizes that all people, regardless of their limitations, have a capacity to learn new skills and live a worthwhile life. AHRC primarily serves adults with mental retardation and developmental disabilities attributable to autism and traumatic brain injury; and, serves children whose developmental delays are significant and attributable to many causal factors.

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An individual is considered to have mental retardation based upon the following three criteria: his/her intellectual functioning level as measured by an IQ test is below 70; he/she has significant limitations in two or more adaptive skill areas (which might include communication, self-care, home living, social skills, community use, self-direction, health and safety, functional academics, leisure and work); and the condition is present from childhood (defined as age 18 or earlier). Mental retardation is not a disease, nor should it be confused with mental illness. About 85 percent of people with the condition fall within the mild range of disability, whereas the remaining 15 percent have more severe disabilities.

The prevalence rate of mental retardation in the United States is between 2.5 and 3 percent of the general population, or an estimated 6.2 to 7.5 million people based on the 1990 census. Mental retardation is 12 times more common than cerebral palsy and affects 100 times as many people as total blindness. One out of every ten families is directly affected.

There are currently over 300 known organic and acquired causes of mental retardation. For instance, the most common chromosomal cause is Down syndrome, whereas the most commonly known single gene cause is Fragile X syndrome. But these are only two of many different etiologies and make up a small percent of those diagnosed with the condition. In addition to the long list of organic causes, adverse environmental and social factors (which include poverty, lack of prenatal care, drug or alcohol abuse during pregnancy resulting in FAS - fetal alcohol syndrome) are placing greater and greater numbers of individuals at-risk for mental retardation. In spite of all that is known, in 50 percent of all cases of mental retardation there is no known specific cause.

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In the diagnostic manual used to classify disabilities, the DSM-IV (American Psychiatric Association, 1994), autistic disorder is listed as a category under the heading "Pervasive Developmental Disorders (PDD’s)" which also includes Asperger syndrome, Rett syndrome, Williams syndrome, and pervasive developmental disorder - not otherwise specified (PDD-NOS). These PDD’s are developmental disabilities that share many of the same characteristics (twelve characteristics are listed with different disorders being defined by the presence of some or the twelve characteristics), are usually evident by the age of three, and affect, to a different degree, an individual child’s ability to communicate, understand language, play and relate to others.

Autism specifically, is defined by federal education law as "a developmental disability significantly affecting verbal and nonverbal communication and social interaction...that adversely affects a child’s educational performance. Other characteristics associated with autism are engagement in repetitive activities and stereotyped movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences." Individuals with autism vary widely in their intelligence and abilities, as well as in the behaviors they exhibit.

Estimates on the prevalence of autism vary, ranging from 5 to 15 out of 10,000 live births. Autism and PDD’s are four times more common in boys than girls. The causes of autism and PDD are unknown. Currently, researchers are investigating areas such as neurological damage and biochemical imbalances of the brain, whereas in the not too distant past, psychological factors were blamed for the disorder.

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Traumatic brain injury (TBI) is defined as an acquired injury to the brain caused by an external force, resulting in a change in level of consciousness or an anatomical abnormality of the brain, and does not apply to brain injuries that are congenital, degenerative or induced by birth trauma. Every incident of head injury is different. In each individual with TBI the type of injury, the locus of the primary brain damage, the ensuing secondary damage, and the resulting pattern of deficits in the areas of physical, cognitive, psychosocial and/or executive functions, are unique. Factors creating even more diversity are the age of the individual upon sustaining the injury, "who" that individual was prior to injury, the care (if any) received immediately following the injury and subsequent care, and the physical and psychosocial environment surrounding that individual before and after his/her injury.

But regardless of individual differences, a number of underlying facts implicit in the definition of traumatic brain injury constitute a common ground. A traumatic brain injury occurs suddenly in the course of normal development leaving a person significantly changed. Damage to the brain is usually diffuse and widespread (not typically resulting in one kind of deficit), but is not global. And, the brain’s ability to be aware of the changes incurred is frequently impaired. These underlying facts that constitute the basic commonality between individuals with TBI are the very same facts that make these individuals different from those born with mental retardation and other developmental disabilities. Although many of these same specific deficits acquired by individuals who have sustained injuries, if viewed in isolation, are also characteristics of individuals born with developmental disabilities, the gestalt is quite different and their needs are different.

If a person acquires a traumatic brain injury before the age of 21 and manifests developmental problems, that individual is considered to be developmentally disabled. Although quite arbitrary, if the injury occurs at the age of 22 or later and results in disability, it is not considered to be a developmental disability.

There are an estimated five million Americans who annually incur a traumatic brain injury. Research indicates that motor vehicle accidents are the cause of more than 50% of all head injuries, falls are the cause of 20% and assaults and violence are the cause of 12%. TBI is a leading cause of death in children and adolescents. Men are twice as likely as women to suffer traumatic brain injuries. Men and boys under the age of 35 incur head injuries most frequently.

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