Intellectual DisabilityEnglevert Reyes, M. Ed.

What’s in a Name?

• Idiot• Moron• Feeble Minded• Mentally Retarded• Intellectual Disability• AAMR– American Association on Intellectual and

Developmental Disabilities (AAIDD)

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What is the History of Mental Retardation/Intellectual Disabilities?• Early History– Rejection and isolation

• 20th Century– Hospitals and institutions were provided.– Eugenics movement– Rise of advocacy organizations and court challenges– Passage of IDEA in 1975

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Why the Use of Two Terms?

• Mental Retardation vs. Intellectual Disabilities– Negative connotations for MR, but used in

IDEA 04– ID is less stigmatizing, but may be a less clear

term than MR

What is Mental Retardation • An individual is considered to have

mental retardation if:– Intellectual functioning IQ <70– Significant limitations in tow or more

adaptive skill areas– Present from childhood

IDEA Definition

“Mental retardation means significantly subaverage general intellectual functioning existing concurrently with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child’s educational performance.”

AAMR 2002 Definition

“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.”

ICD-10

• Tenth revision of the International Classification of Diseases from the World Health Organization

• Characterizes MR as a condition resulting from a failure of the mind to develop

• Four levels

What are adaptive skills?

Adaptive skill areas are those daily living skills needed to live, work and play in the community

Adaptive Skill Areas• Communication• Self-care• Home living• Social skills• Leisure• Health & safety• Self-direction• Functional academics• Community use• Work

Mild Mental Retardation

• Previously referred to as “educable”• Largest segment of those with MR (85%)• Typically develop social/communication

skills during preschool years, minimal impairment in sensorimotor areas, often indistinguishable from “typicals” until later age

• By late teens acquire skills up to approximately the 6th grade level

Moderate Mental Retardation• Previously referred to as “trainable”• About 10% of those with MR• Most acquire communication skills during early

childhood years• Generally benefit from social/vocational training and

with moderate supervision can attend to personal care• Difficulties recognizing social conventions which

interferes with peer relations in adolescence• Unlikely to progress beyond the 2nd grade academically• Often adapt well to life in the community in supervised

settings (performing unskilled or semiskilled work)

Severe Mental Retardation• 3 – 4% of those with MR• Acquire little or no communicative speech in

childhood; may learn to talk by school age and be trained in elementary self-care skills

• Can master sight reading “survival” words• Able to perform simple tasks as adults in

closely supervised settings• Most adapt well to life in the community,

living in group homes or with families

Profound Mental Retardation

• 1 – 2% of those with MR• Most have an identifiable neurological

condition that accounts for their MR• Considerable impairments in

sensorimotor functioning• Optimal development may occur in a

highly structured environment with constant aid

Prevalence

• 1% (1 – 3% in developed countries)• The prevalence of MR due to biological factors is

similar among children of all SES; however, certain etiological factors are linked to lower SES (e.g., lead poisoning & premature birth)

• More common among males (1.5:1)• In cases without a specifically identified

biological cause, the MR is usually milder; and individuals from lower SES are over-represented

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What are the Causes of Intellectual Disabilities?• Genetic and Chromosomal – Examples

include:– Tuberous Sclerosis, Neurofibromatosis,

PKU, Galactosemia, Hurler Syndrome, Tay Sachs, Hunter Syndrome, Lesch-Nyan Syndrome, Fragile X, Rett Syndrome, Down Syndrome

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What are the Causes of Intellectual Disabilities?• Environmental – Examples include:

– Toxoplasmosis, Rubella, Cytomegalovirus, Radiation, Malnutrition, Maternal Age, Maternal Health, Drug and Substance Abuse, Blood Type Incompatibility

• Psychosocial Factors – Examples include:– Poverty, Malnutrition, Inadequate Health

Care• May contribute to mental retardation rather

than be a direct cause

Prevention• Prenatal care• Newborn screening• Vaccines• Lead removal• Child safety

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What are Possible Characteristics of Students with Intellectual Disabilities?• Difficulties learning• Deficits in social-personal skills• Deficits in adaptive behavior skills• Attention difficulties• Memory deficits• Difficulty transferring and generalizing skills• Speech and Language delays

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How are Students with Mental Retardation Identified?• Intelligence Testing (IQ below 70-75)• Adaptive Skills Assessments (deficits in

adaptive skills)• Academic Skills Assessments (adversely

affects educational performance)

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What Do I Teach Students with Intellectual Disabilities?• Person-centered planning• Basic academic skills• Functional curriculum– Functional academics, independent life

skills, self-determination, self-advocacy

• Community-based instruction• Transition planning

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How Do I Teach Students with Intellectual Disabilities?• Direct instruction with clear objectives,

advance organizers, “think-aloud” model, guided practice, independent practice, post-organizers– Focus on task analysis– Focus on sequencing tasks for recognition, recall,

reconstruction– Focus on presentation and practice, including use of

prompts

• Generalization

Down Syndrome (trisomy 21 syndrome)

• Down syndrome has been the most investigated, and most discussed syndrome in mental retardation.

• Children with this syndrome were originally called mongoloid because of their physical characteristics of slanted eyes, epicanthal folds, and flat nose.

• Despite a plethora of theories and hypotheses advanced in the past 100 years, the cause of Down syndrome is still unknown.

A. A young child with Down syndrome. B. A young adult with fragile X syndrome.

Fragile X Syndrome• Fragile X syndrome is the second most common

single cause of mental retardation.• The syndrome results from a mutation on the X

chromosome at what is known as the fragile site (Xq27.3).

• The typical phenotype includes a large, long head and ears, short stature, hyperextensible joints, and postpubertal macroorchidism.

• The mental retardation ranges from mild to severe.

Martin-Bell

syndromeFragile X syndrome is believed to occur in about 1 of every 1,000 males and 1 of every 2,000 females.

Fragile X Syndrome

Prader-Willi Syndrome• Prader-Willi syndrome is postulated to result

from a small deletion involving chromosome 15, usually occurring sporadically.

• Its prevalence is less than 1 of 10,000. • Persons with the syndrome exhibit compulsive

eating behavior and often obesity, mental retardation, hypogonadism, small stature, hypotonia, and small hands and feet.

• Children with the syndrome often have oppositional and defiant behavior.

Prader-Willi Syndrome

Cat's Cry (Cri-du-Chat) Syndrome

• Children with cat's cry syndrome lack part of chromosome 5.

• They are severely retarded andshow many signs often associated with chromosomal aberrations, such as microcephaly, low-set ears, oblique palpebral fissures, hypertelorism, and micrognathia.

• The characteristic cat-like cry caused by laryngeal abnormalities that gave the syndrome its name gradually changes and disappears with increasing age.

Cri-du-Chat Syndrome

Cri-du-Chat Syndrome

Phenylketonuria• PKU was first described by Ivar Asbjörn Fölling

in 1934 as the paradigmatic inborn error of metabolism. PKU is transmitted as a simple recessive autosomal mendelian trait and occurs in about 1 of every 10,000 to 15,000 live births.

• The basic metabolic defect in PKU is an inability to convert phenylalanine, an essential amino acid, to paratyrosine because of the absence or inactivity of the liver enzyme phenylalanine hydroxylase, which catalyzes the conversion.

Phenylketonuria• Most patients with PKU are severely retarded, but

some are reported to have borderline or normal intelligence. Eczema, vomiting, and convulsions occur in about a third of all patients.

• They frequently have temper tantrums and often display bizarre movements of their bodies and upper extremities, including twisting hand mannerisms; their behavior sometimes resembles that of children with autism or schizophrenia.

Rett's Disorder• Rett's disorder is hypothesized to be an X-

linked dominant mental retardation syndrome that is degenerative and affects only females.

• Deterioration in communications skills, motor behavior, and social functioning starts at about 1 year of age. Autistic-like symptoms are common, as are ataxia, facial grimacing, teeth-grinding, and loss of speech.

Rett's Disorder

Neurofibromatosis• Also called von Recklinghausen's disease,

neurofibromatosis is the most common of the neurocutaneous syndromes caused by a single dominant gene, which may be inherited or be a new mutation. The disorder occurs in about 1 of 5,000 births. and is characterized by cafe au lait spots on the skin and by neurofibromas, including optic gliomas and acoustic neuromas, caused by abnormal cell migration.

• Mild mental retardation occurs in up to one third of those with the disease.

Tuberous Sclerosis

• Tuberous sclerosis is the second most common of the neurocutaneous syndromes; a progressive mental retardation occurs in up to two thirds of all affected persons.

• It occurs in about 1 of 15,000 persons and is inherited by autosomal dominant transmission.

Tuberous Sclerosis

Lesch-Nyhan Syndrome

• Lesch-Nyhan syndrome is a rare disorder caused by a deficiency of an enzyme involved in purine metabolism.

• The disorder is X-linked; patients have mental retardation, microcephaly, seizures, choreoathetosis, and spasticity.

Lesch-Nyhan Syndrome

Adrenoleukodystrophy• The most common of several disorders of sudanophilic

cerebral sclerosis, adrenoleukodystrophy is characterized by diffuse demyelination of the cerebral white matter resulting in visual and intellectual impairment, seizures, spasticity, and progression to death.

• The disorder is transmitted by a sex-linked gene located on the distal end of the long arm of the X chromosome.

• The clinical onset is generally between 5 and 8 years of age, with early seizures, disturbances in gait, and mild intellectual impairment.

Adrenoleukodystrophy

• The story of a child with the disorder was presented in the 1992 film Lorenzo's Oil.

Maple Syrup Urine Disease• An inborn error of metabolism caused by defective

oxidative decarboxylation of )-keto acids of leucine, isoleucine, and valine.

• These branched-chain amino acids are present in the blood and urine in high concentrations.

• Manifestations of disease include feeding difficulties, physical and mental retardation, and a urine odor similar to that of maple syrup; neonatal death is common.

Fetal Alcohol Syndrome

• A typical phenotypic picture of facial dysmorphism that includes hypertelorism, microcephaly, short palpebral fissures, inner epicanthal folds, and a short, turned-up nose.

• The entire syndrome occurs in up to 15 percent of babies born to women who regularly ingest large amounts of alcohol.