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Intellectual Functioning & Adaptive Functioning• The conceptualization of mental retardation includes deficits in cognitive abilities as well as in behaviors required for social and personal sufficiency, known as adaptive functioning.• Measures of adaptive function assess competency in performance of everyday tasks, whereas measures of intellectual function focus on cognitive abilities.
Organizations• The most prominent advocacy organization in this field is the American Association on Mental Retardation (AAMR), which has been most influential in educating the public about mental retardation and in supporting research and legislation relating to mental retardation.• The AAMR promotes designating an IQ of 75, rather than 70, as the beginning level of the mild mental retardation range, thereby enabling many more persons to receive services as mentally retarded.
Nomenclature• According to DSM-IV-TR, a diagnosis of mental retardation can be made only when both the IQ, as measured by a standardized test, is subaverage and a measure of adaptive function reveals deficits in at least two of the areas of adaptive function.• Mental retardation diagnoses are coded on Axis II in the DSM-IV-TR.
Classification• According to the DSM-IV-TR, mental retardation is defined as significantly subaverage general intellectual functioning resulting in, or associated with, concurrent impairment in adaptive behavior and manifested during the developmental period, before the age of 18.• The diagnosis is made regardless of whether the person has a coexisting physical disorder or other mental disorder.
Degrees of Mental Retardation1) Mild2) Moderate3) Severe4) Profound Term significantly subaverage is defined as an IQ of approximately 70. Adaptive functioning can be measured by using a standardized scale, such as the Vineland Adaptive Behavior Scale.
Degrees of Severity of Mental Retardation• Borderline intellectual functioning, according to DSM-IV-TR, is not within the diagnostic boundary of mental retardation and refers to a full-scale IQ in the 71 to 84 range that is a focus of psychiatric attention.• Mild mental retardation (IQ range, 50 to 70) represents approximately 85 percent of persons with mental retardation.• Many adults with mild mental retardation can live independently with appropriate support and raise their own families.
Moderate Mental Retardation• Moderate mental retardation (IQ range, 35-50) represents about 10 percent of persons with mental retardation.• They are challenged academically and often are not able to achieve academically above a second to third grade level.• As adults, persons with moderate mental retardation may be able to perform semiskilled work under appropriate supervision.
• Severe mental retardation (IQ range, 20-35) comprises about 4 percent of individuals with mental retardation.• In adulthood, persons with severe mental retardation may adapt well to supervised living situations, such as group homes, and may be able to perform work-related tasks under supervision.
Profound Mental Retardation• Profound mental retardation (IQ range below 20) constitutes approximately 1 to 2 percent of persons with mental retardation.• Most individuals with profound mental retardation have identifiable causes for their condition.• Children with profound mental retardation may be taught some self-care skills and learn to communicate their needs given the appropriate training.
Mental Retardation, Severity Unspecified• The DSM-IV-TR lists mental retardation, severity unspecified, as a type reserved for persons who are strongly suspected of having mental retardation, but who cannot be tested by standard intelligence tests or are too impaired or uncooperative to be tested.• This type may be applicable to infants whose significantly subaverage intellectual functioning is clinically judged but for whom the available tests (e.g., Bayley Scales of Infant Development and Cattell Infant Scale) do not yield numerical IQ values.• This type should not be used when the intellectual level is presumed to be above 70.
Epidemiology• Prevalence- 1% to 3%.• Highest incidence- school-age children with the peak at the ages 10 to 14 years.• 1.5 times more common among men than among women.
COMORBIDITY Prevalence• A recent epidemiological study found that 40.7 percent of intellectually disabled children between 4 and 18 years of age met criteria for at least one psychiatric disorder.• The severity of retardation affected the type of psychiatric disorder.• The mental disorders that occur among persons who are mentally retarded appear to run the gamut of those seen in persons not mentally retarded, including mood disorders, schizophrenia, attention- deficit/hyperactivity disorder (ADHD), and conduct disorder.
Neurological Disorders• In a recent review of psychiatric disorders in children and adolescents with mental retardation and epilepsy, approximately one third also had autistic disorder or an autistic- like condition.• The combination of mental retardation, active epilepsy, and autism or an autistic-like condition occurs at a rate of 0.07 percent in the general population.
Psychosocial Features• A negative self-image and poor self-esteem are common features of mildly and moderately mentally retarded persons, who are well aware of being different from others.• The perpetual sense of isolation and inadequacy has been linked to feelings of anxiety, anger, dysphoria, and depression.
Etiology• Overall, in up to two thirds of all mentally retarded persons, the probable cause can be identified.• Among chromosomal and metabolic disorders, Down syndrome, fragile X syndrome, and phenylketonuria (PKU) are the most common disorders that usually produce at least moderate mental retardation. Those with mild mental retardation sometimes have a familial pattern apparent in parents and siblings.• Deprivation of nutrition, nurturance, and social stimulation can contribute to the development of mental retardation. Current knowledge suggests that genetic, environmental, biological, and psychosocial factors work additively in mental retardation.
Genetic Etiological Factors in Mental Retardation• Abnormalities in autosomal chromosomes- mental retardation.• Aberrations in sex chromosomes- physical syndromes that do not include mental retardation (e.g., Turners syndrome with XO and Klinefelters syndrome with XXY, XXXY, and XXYY variations).• Agreement exists on a few predisposing factors for chromosomal disorders- among them, advanced maternal age, increased age of the father, and X-ray radiation.
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. Ayoung 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 tooccur in about 1 of every 1,000males and 1 of every 2,000females.
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.
Cats Cry (Cri-du-Chat) Syndrome• Children with cats cry syndrome lack part of chromosome 5.• They are severely retarded and show 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.
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.
Retts Disorder• Retts 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.
Neurofibromatosis• Also called von Recklinghausens 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.
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.
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 Lorenzos 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• Prenatal Drug Exposure• Complications of Pregnancy• Perinatal Period• Acquired Childhood Disorders• Infection• Head Trauma• Other Issues
Prenatal Period• Maternal chronic illnesses affecting the normal development of the fetuss CNS include uncontrolled diabetes, anemia, emphysema, hypertension, and long-term use of alcohol and narcotic substances.• The extent of fetal damage depends on the type of viral infection, the gestational age of the fetus, and the severity of the illness.
Rubella (German Measles)• the major cause of mental retardation caused by maternal infection.• The children of affected mothers may show several abnormalities, including congenital heart disease, mental retardation, cataracts, deafness, microcephaly, and microphthalmia.• The incidence rises to almost 50 percent when the infection occurs in the first month of pregnancy.
Cytomegalic Inclusion Disease• Some children are stillborn, and others have jaundice, microcephaly, hepatosplenomegaly, and radiographic findings of intracerebral calcification.• The diagnosis is confirmed by positive findings of the virus in throat and urine cultures.
Syphilis• The incidence of syphilitic complications of pregnancy fluctuates with the incidence of syphilis in the general population.
• Toxoplasmosis• It causes mild or severe mental retardation and, in severe cases, hydrocephalus, seizures, microcephaly, and chorioretinitis.• Herpes Simplex• The herpes simplex virus can be transmitted transplacentally, although the most common mode of infection is during birth.• Microcephaly, mental retardation, intracranial calcification, and ocular abnormalities may result.
Acquired Immune Deficiency Syndrome (AIDS)• Many fetuses of mothers with AIDS never come to term because of stillbirth or spontaneous abortion.• Children born with HIV infection often live only a few years; however, most babies born to HIV- infected mothers are not infected with the virus.
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
Complications of Pregnancy• Toxemia of pregnancy and uncontrolled maternal diabetes result in mental retardation.• Maternal malnutrition during pregnancy often results in prematurity and other obstetrical complications.• Vaginal hemorrhage, placenta previa, premature separation of the placenta, and prolapse of the cord can damage the fetal brain by causing anoxia
Infection• The most serious infections affecting cerebral integrity are encephalitis and meningitis.• Most episodes of encephalitis are caused by viruses.• Sometimes a clinician must retrospectively consider a probable encephalitic component in a previous obscure illness with high fever.
Head Trauma• The best-known causes of head injury in children that produces developmental handicaps, including seizures, are motor vehicle accidents, but more head injuries are caused by household accidents, such as falls from tables, from open windows, and on stairways.
Diagnosis• History• The history is most often obtained from the parents or the caretaker, with particular attention to the mothers pregnancy, labor, and delivery.• The clinician assesses the overall level of functioning and intellectual capacity of the parents and the emotional climate of the home.
Diagnosis• Psychiatric Interview• Two factors are of paramount importance when interviewing the patient:• 1) the interviewers attitude .• 2) manner of communicating.• A mildly retarded adult with a mental age of 10 is not a 10-year-old child.• When addressed as if they were children, some retarded persons become justifiably insulted,
• The patients verbal abilities, including receptive and expressive language, should be assessed as soon as possible by observing the communication between the caretakers and the patient and by taking the history.• The interviewer and the caretaker should attempt to give such patients a clear, supportive, concrete explanation of the diagnostic process, particularly patients with sufficiently receptive language.
• The use of speech, reality testing, and the ability to generalize from experiences should be noted.• Frustration, tolerance, and impulse control, especially over motor, aggressive, and sexual drive should be assessed.
Physical Examination• the configuration and the size of the head offer clues to a variety of conditions, such as microcephaly, hydrocephalus, and Down syndrome.• patients face may have some signs of mental retardation that greatly facilitate the diagnosis, such as hypertelorism, a flat nasal bridge, prominent eyebrows, epicanthal folds, corneal opacities, retinal changes.
• The circumference of the head should be measured as part of the clinical investigation.• Dermatoglyphics may offer another diagnostic tool, because uncommon ridge patterns and flexion creases on the hand are often found in persons who are retarded.
• Table 38-4 Representative Sample of Mental Retardation Syndromes and Behavioral Phenotypes
Neurological Examination• Sensory impairments occur frequently among persons who are mentally retarded.• Disturbances in motor areas are manifested in abnormalities of muscle tone (spasticity or hypotonia), reflexes (hyperreflexia), and involuntary movements (choreoathetosis).
• In older children, hyperactivity, short attention span, distractibility, and a low frustration tolerance are often signs of brain damage.• The younger the child at the time of investigation, the more caution is indicated in predicting future ability, because the recovery potential of the infantile brain is very good.
• Skull X-rays: craniosynostosis, hydrocephalus, and intracranial calcifications.• Computed tomography (CT) scans and magnetic resonance imaging (MRI) : CNS pathology associated with mental retardation.• An EEG is best interpreted with caution in cases of mental retardation.• exceptions are patients with hypsarhythmia and grand mal seizures, in whom the EEG may help establish the diagnosis and suggest treatment
Clinical Features• Mild mental retardation may not be diagnosed until the affected children enter school; their social skills and communication may be adequate in the preschool years.• Moderate mental retardation is likely to be diagnosed at a younger age than mild mental retardation; communication skills develop more slowly in persons who are moderately retarded, and their social isolation may begin in the elementary school years.• Severe mental retardation is generally obvious in
Laboratory Examination• chromosomal analysis,• urine and blood testing for metabolic disorders,• neuroimaging.• Chromosomal abnormalities are the single most common cause of mental retardation found in individuals for whom a cause can be identified.
Chromosome Studies• Amniocentesis, in which a small amount of amniotic fluid is removed from the amniotic cavity transabdominally at about the 15th week of gestation, has been useful in diagnosing prenatal chromosomal abnormalities.• it should be considered by pregnant women over the age of 35.• Chronic villi sampling (CVS) is a screening technique to determine fetal chromosomal abnormalities.• 8 to 10 weeks of gestation
Urine and Blood Analysis• Lesch-Nyhan syndrome,• Galactosemia,• PKU,• Hurlers syndrome,• Hunters syndrome,• Unexplained growth abnormality,• Seizure disorder,• poor muscle tone, ataxia, bone or skin abnormalities, and eye abnormalities are some indications for testing metabolic function.
Neuroimaging• Biological mechanisms contributing to mental retardation syndromes.• MRI can show abnormalities in the brain such as myelination patterns.
Two brothers, age 6 and 8 years, with Hunters syndrome, shown with theirnormal older sister. They have had significant developmental delay, troublewith recurrent respiratory infection, and behavioral abnormalities.
Hearing and Speech Evaluations• Speech development may be the most reliable criterion in investigating mental retardation.• The commonly used methods of hearing and speech evaluation, however, require the patients cooperation and, are often unreliable in severely retarded persons.
Psychological Assessment• the Goodenough Draw-a-Person Test, the Kohs Block Test, and geometric puzzles all may be used as quick screening tests of visual-motor coordination.• The Gesell and Bayley scales and the Cattell Infant Intelligence Scale are most commonly used with infants.• For children, the Stanford-Binet Intelligence Scale and the third edition of the Wechsler Intelligence Scale for Children (WISC-III) are those most
Psychological Assessment• Some persons have tried to overcome the language barrier of persons who are mentally retarded by devising picture vocabulary tests, of which the Peabody Vocabulary Test is the one most widely used.• The tests often found useful in detecting brain damage are the Bender Gestalt Test and the Benton Visual Retention Test
Differential Diagnosis• Several sensory disabilities, especially deafness and blindness, can be mistaken for mental retardation.• Speech deficits .• cerebral palsy .• Convulsive disorders.• Chronic brain syndromes can result in isolated handicap failure to read (alexia), failure to write (agraphia), failure to communicate (aphasia),
• Mental retardation and pervasive developmental disorders often coexist;• 70 to 75 percent of those with pervasive developmental disorders have an IQ below 70.• A most difficult differential diagnostic problem concerns children with severe mental retardation, brain damage, autistic disorder, schizophrenia with childhood onset, or, according to some, Hellers disease.
• Children under the age of 18 years who meet the diagnostic criteria for dementia and who have an IQ below 70 are given the diagnoses of dementia and mental retardation.
Treatment• based on an assessment of social, educational, psychiatric, and environmental need.• Primary Prevention• education to increase the general publics knowledge and awareness of mental retardation;• continuing efforts of health professionals to ensure and upgrade public health policies;• legislation to provide optimal maternal and child health care
Treatment Secondary and Tertiary Prevention• should be treated to shorten the course of the illness.• to minimize the sequelae or consequent disabilities.• Hereditary metabolic and endocrine disorders, such as PKU and hypothyroidism, can be treated effectively in an early stage.
Treatment• Education for the Child• Behavioral, Cognitive, and Psychodynamic Therapies• Family Education• Social Intervention
Treatment• Pharmacology• some studies have focused on the use of medications for the following behavioral syndromes that are frequent among persons who are mentally retarded
Treatment• Common Comorbid Psychiatric Disorders• Attention-Deficit/Hyperactivity Disorder: methylphenidate (Ritalin), risperidone (Risperdal)• 1.6 mg a day for a period of 1 year• Aggression and Self-Injurious Behavior:• lithium (Eskalith),
Treatment• Note: Persons with mental retardation appear to be at higher risk for the development of tardive dyskinesia after use of a variety of antipsychotic medications.• For tardive dyskinesia- risperidone and clozapine
ICD-10• Approaches the diagnosis of mental retardation from a somewhat different viewpoint than DSM-IV-TR.• According to ICD-10, mental retardation is a condition arrested or incomplete development of the mind• characterized by impaired developmental skills that contribute to the overall level of intelligence.
Services and Support for Children with Mental Retardation• Early Intervention• School• Supports