MENTAL RETARDATION

MENTAL RETARDATION

Mental retardation (MR)is the term used when people demonstrate substantial limitations in intellectual functioning and adaptive behaviour that affect daily living.the limitations are observed in conceptual (e.g receptive and expressive language),social (e.g ability to follow rules ,inter personal skills)and practical adaptive (e.g using telephone using transportation )skills.This disability originates before the age of 18.

Hence the definition given by AAMR(2002)can be:

“Mental retardation is a disability characterized by significant limitation both in intellectual functioning and adaptive behaviour as expressed in conceptual,social and practical adaptive skills”

Grossman(1973)gave definition of MR which is stated as

“Mental retardation refers to significantly sub average,general intellectual functioning ,existing concurrently with deficits in adaptive behaviour and manifested during the developmental period”

·        Significantly sub average is generally defined as an IQ  of 70 or lower but this upper limit may be extended upward ,depending on the reliability of the testing that helped to establish IQ.

·        Intellectual functioning refers to results of standardized general intelligence test.The generally accepted measurement of intelligence is IQ  ,which is a ratio of mental age to chronological age.

·        Deficits in adaptive behaviour refers to limitations in two or more adaptive skills  areas i.e communication ,self care functional academics ,self-direction,home living,social skills,community use ,health and safety,leisure and work.

·        Developmental period refers to the period prior to age 18.For  those with MR development may be slow,arrested or incomplete.

Classification of mental retardation

Earlier  classification system proposed by American association of mental deficiency in 1910 referred to individuals with MR as feeble minded meaning that their development was halted at an early age or was inadequate making it difficult to keep peer and manage their daily lives independently.three levels of impairment were identified.

Idiot :Individual whose development is arrested at age of 2 years.

Imbecile:Individual whose development is equivalent to that of 2-7 year old.

Moron:Individual  whose mental development is equivalent to that of 7-12 year old.

Informational classification of diseases(ICD-10)gave 4 levels of MR .

170-mild (IQ=50-69)

171-moderate(IQ=35-49)

172-severe(IQ=20-34)

173=profound(IQ=below 20)

178=To be used when MR is associated with physical or sensory impairment

179= To be used when there is evidence of MR but not enough information is obtained to establish a level of functioning.

Also ,based on lewis M.Terman who developed original Stanford-Binet intelligence Test ,individuals were classified into 3 broad ranges of MR.

Morons-IQ=50-70

Imbecile-IQ=30-50

Idiots-IQ=0-30

Idiots are unable to care for themselves unless they are given special and prolonged training.

Imbecile –Able to learn to dress and engage in useful personal functions provided they are given appropriate training.

Moron –Able to profit considerably from carefully tailored training and education .They were able to take care of their basic physiological needs, communicate effectively and are able to learn to read and write.

       MMR(1992)gave categories of MR ,which is depicted  in a tabular form:

Category	IQ range	%of MR population	characteristics
Mild	52-68	89	Usually observed into the community ,when they work and live independently
Moderate	36-51	6	Capable of learning self care skills and working within a sheltered environment live semi independently with relatives or in community residence.
severe	20-35	3.5	Capable of learning some self care skills an are not totally dependent,often exhibit physical disabilities and deficits in special living.
profound	Below 20	1.5	Capable of learning some basic living skills but require continual care and supervision

Other Methods For Classifying Mental Retardation:

American clinical classification (Now obsolete)	Educational classification	AAMD  Intellectual levels	IQ Range	Mental age expectancy
Borderline retardation	Slow learner	Borderline intelligence	69-80	13
Moron	Educable	Mild	52-68	8-12
Imbecile	Trainable	Moderate severe	36-51 20-35	3-7
Idiot	Custodial	Profound	Below 20	0-3

Most commonly used method in grading severity of MR is based on classification gives by Goodman so ,according to level of IQ ,severity is graded,

80-90-Dull normal

70-79-Borderline MR

50-69-Mild MR

35-49-Moderate MR

20-34-Severe MR

<20-profound MR

Causes of Mental Retardation

            Mental retardation has many causes .Most of these causes are presumed because of their frequent association with retardation.some of the causes are environmentally reduced whereas others are genetic. However even genetic causes may have an environmental origin.

Factors that are associated with MR are classified in different ways.The following is one method of classification:

1)MR associated with prenatal infections or toxicity

2)MR associated with natal conditions

3)MR associated with post nasal poisonings or toxicity

4)MR associated with head trauma

5)MR associated with metabolic disorders

6)MR associated with endocrine disorders

7)MR associated with cranial abnormalities

8)MR associated with genetic defects

1) Prenatal factors include Rubella, prenatal lead poisoning, maternal anoxia, X- ray and radiation etc.

2) Natal factors include Fetal Anoxia, other kinds of brain injury at birth

3) Postnatal factors includes Lead Poisoning, vaccination

4) Head Trauma can be accidents, wounds.

5) Metabolic disorders like PKU, lipid metabolic errors

6) Endocrine disorders such as Hypothyroidism

7) Cranial abnormalities like Microcephaly, Hydrocephaly

Genetic syndromes tike Down syndrome, Fragile X syndrome, Cri-du chat syndrome

Genetic perspectives on MR: Genetic causes accounts approx. 45% of cases of MR (Batshow and Ferret 1992)    Genetic influences in severe MR were usually discussed mainly in terms of Mendelian disorders and chromosomal abnormalities associated with it.

Few syndromes that issue the role of genetics on MR are:

1)      Down's syndrome

2)      Fragile X syndrome   

3)      Williams syndrome

It has been found that children with genetic alternation in a gene called Qoxiblecfidia-sdffer from epilepsy and MR is due to the defect in poisoning the neuronal stem cells within the cerebral cortex. In the normal brain, neurons are born adjacent to fluid filled cavities deep within developing brain during 3^rd and 4^th month of gestation after which they must migrate to reach their proper position within 6 layered cortex. When this migration is defective and neurons do not reach proper destination there is absence of normal groves and ridges. Only 4 instead of 6 layers of cortex are formed and cerebral cortex of these patients lacks groves and ridges.

STUDY

Matching-to-sample and stimulus-equivalence training is effective for teaching expressive use of manual signs to adults with mental retardation(James K. Luiselli )

 (Evidence-Based Communication Assessment and Intervention, Volume 2, Issue 4 December 2008 )

AIM

Whether matching-to-sample and stimulus-equivalence training is effective for teaching expressive use of manual signs to adults with mental retardation?

Results

•         Following MTS (conditional discrimination) training, the percentage of correct responding by participants during expressive signing tests ranged from 0% to 100%.

•          Results vaired within and between participants, relative to picture-sign and word-sign relationships.

•         Test performance by the participants was generally superior for the first set of trained stimuli, compared with later stimuli sets.

Down Syndrome

Also called 'Prince Charming Syndrome* (Menolascino, 1965) because they are cheerful, affectionate, friendly and eager to please. At the same time they are stubborn, aggressive behavior. Both personality strength & behavior problems seen variably expressed within & between persons with DS.

Prevalence estimates are higher & more variable in studies of children & adolescents ranging from 18% to 38% (Gath & Gumley, 1986; Meyeis & Pusehel, 1991). Approximate 95% of children with DS have extra 21^st chromosome in each which is called Trisomy 21 or Nondisjunction Trisomy 21. Another type called translocation DS have extra 21^st chromosome in which long arm attaches to the other chromosome usually 14, 21, 22.  1-2% of individuals with DS have extra chromosome in some cells & not at all cells. This type is called Mongolism.

Miller (1988) reported 75% demonstrated deficits in language production than comprehension & cognitive skills.

Wide variety of vocabulary development of DS is similar to that of typically developing children (Cardoso-Martins, Mervis & Mervis 1985, 1997) but there is slower rate of development.

Literature documents 1^st spoken word at an average of 18 months in children with DS (Gilham, 1979).

Syntax presents more difficulty because it is more abstract & exhibit greater difficulty in developing or using prepositions, connectives & other functional words (Fowler, 1990; Miller, 1987, 1988)

Pragmatics & social interactive language are strengths for children with DS. Though they may have difficulty with specific pragmatic skills, children with DS seek social interaction & use gestures & facial expression to enhance their verbal language.

    Down syndrome, Down's syndrome, or trisomy 21 is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British doctor who described the syndrome in 1866. The disorder was identified as a chromosome 21 trisomy by Jérôme Lejeune in 1959. The condition is characterized by a combination of major and minor differences in structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Down syndrome in a baby can be identified with amniocentesis during pregnancy or at birth.

Individuals with Down syndrome tend to have a lower than average cognitive ability, often ranging from mild to moderate developmental disabilities. A small number have severe to profound mental disability. The incidence of Down syndrome is estimated at 1 per 800 to 1,000 births, although these statistics are heavily influenced by the age of the mother. Other factors may also play a role.

Many of the common physical features of Down syndrome also appear in people with a standard set of chromosomes. They may include a single transverse palmar crease (a single instead of a double crease across one or both palms, also called the Simian crease), an almond shape to the eyes caused by an epicanthic fold of the eyelid, upslanting palpebral fissures (the separation between the upper and lower eyelids), shorter limbs, poor muscle tone, a larger than normal space between the big and second toes, and protruding tongue. Health concerns for individuals with Down syndrome include a higher risk for congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions.

Early childhood intervention, screening for common problems, medical treatment where indicated, a conducive family environment, and vocational training can improve the overall development of children with Down syndrome. Although some of the physical genetic limitations of Down syndrome cannot be overcome, education and proper care will improve quality of life.

 

Characteristics

Example of white spots on the iris known as Brushfield spots

Individuals with Down syndrome may have some or all of the following physical characteristics: oblique eye fissures with epicanthic skin folds on the inner corner of the eyes, muscle hypotonia (poor muscle tone), a flat nasal bridge, a single palmar fold, a protruding tongue (due to small oral cavity, and an enlarged tongue near the tonsils), a short neck, white spots on the iris known as Brushfield spots,^[2] excessive joint laxity including atlanto-axial instability, congenital heart defects, excessive space between large toe and second toe, a single flexion furrow of the fifth finger, and a higher number of ulnar loop dermatoglyphs. Most individuals with Down syndrome have mental retardation in the mild (IQ 50–70) to moderate (IQ 35–50) range,^[3] with individuals having Mosaic Down syndrome typically 10–30 points higher.^[4] In addition, individuals with Down syndrome can have serious abnormalities affecting any body system. They also may have a broad head and a very round.

Cognitive development in children with Down syndrome is quite variable. It is not currently possible at birth to predict the capabilities of any individual reliably, nor are the number or appearance of physical features predictive of future ability. The identification of the best methods of teaching each particular child ideally begins soon after birth through early intervention programs.^[33] Since children with Down syndrome have a wide range of abilities, success at school can vary greatly, which underlines the importance of evaluating children individually. The cognitive problems that are found among children with Down syndrome can also be found among typical children. Therefore, parents can use general programs that are offered through the schools or other means.

Language skills show a difference between understanding speech and expressing speech and commonly individuals with Down syndrome have a speech delay, require speech therapy to improve expressive language.^[34] Fine motor skills are delayed^[35] and often lag behind gross motor skills and can interfere with cognitive development. Effects of the disorder on the development of gross motor skills are quite variable. Some children will begin walking at around 2 years of age, while others will not walk until age 4. Physical therapy, and/or participation in a program of adapted physical education (APE), may promote enhanced development of gross motor skills in Downs Syndrome children.^[36]

Individuals with Down syndrome differ considerably in their language and communication skills. It is routine to screen for middle ear problems and hearing loss; low gain hearing aids or other amplification devices can be useful for language learning. Early communication intervention fosters linguistic skills. Language assessments can help profile strengths and weaknesses; for example, it is common for receptive language skills to exceed expressive skills. Individualized speech therapy can target specific speech errors, increase speech intelligibility, and in some cases encourage advanced language and literacy. Augmentative and alternative communication (AAC) methods, such as pointing, body language, objects, or graphics are often used to aid communication.

STUDY

The Role of Color Cues in Facilitating Accurate and Rapid Location of Aided Symbols by Children With and Without Down Syndrome

Krista Wilkinson , Michael Carlin , Jennifer Thistle

American Journal of Speech-Language Pathology Vol.17 179-193 May 2008.

AIM

How the color distribution of symbols within a visual aided augmentative and alternative communication array influenced the speed and accuracy with which participants with and without Down syndrome located a target picture symbol.

Results  

Clustering same-color symbols facilitated the speed of locating the target for all participants, and facilitated search accuracy in the younger preschool children and participants with Down syndrome.

Clinicians should consider the internal color of visual symbols when constructing aided symbol displays, at least for children with Down syndrome.

William’s Syndrome

Williams syndrome (WS; also Williams-Beuren syndrome or WBS) is a rare neurodevelopmental disorder caused by a deletion of about 26 genes from the long arm of chromosome 7.^[1] It is characterized by a distinctive, "elfin" facial appearance, along with a low nasal bridge; an unusually cheerful demeanor and ease with strangers; mental retardation coupled with unusual (for persons who are diagnosed as mentally retarded) language skills; a love for music; and cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcaemia. The syndrome was first identified in 1961 by Dr. J. C. P. Williams of New Zealand.

Also called as Benson syndrome & previously was known as Infantile Hypocalcemia

Rare congenital metabolic disorder characterized by ‘elfin like’ facial appearance in some subjects, a star like pattern in iris, depressed nasal bridge, cardiac deficits in about 80% of cases.

Symptoms

Individuals with Williams syndrome are highly verbal and sociable (having what has been described as a "cocktail party" type personality), but lack common sense and typically have inhibited intelligence. Individuals with WS hyperfocus on the eyes of others in social engagements.^[3] Phenotypically patients tend to have widely spaced teeth, a long philtrum, and flattened nasal bridge.^[4]

People with Williams syndrome often have hyperacusis and phonophobia which resembles noise-induced hearing loss, but this may be due to a malfunctioning auditory nerve.^[5][6] Individuals with the condition tend to demonstrate a love of music^[4], and also appear significantly more likely to possess perfect pitch.^[7]

There also appears to be a higher prevalence of left-handedness and left-eye dominance in those with Williams.^[8] Individuals with Williams syndrome also report higher anxiety levels as well as phobia development, which may be associated with hyperacusis.^[9]

Visual perception

Individuals with Williams syndrome have problems with visual processing, but this is related to difficulty in dealing with complex spatial relationships rather than to issues with depth perception.^[10]

Treatment

No curative therapy is known for Williams syndrome, and care is mostly supportive.^[4] Guidelines published by the American Academy of Pediatrics include cardiology evaluations, developmental and psychoeducational assessment, and many other examination, laboratory, and anticipatory guidance recommendations.

Researchers have found that most individuals with William syndrome have a deletion of genetic material  from the region q11.23 of chromosome 7. CLIP2, ELN, GTF2I, GTF2IRD1, and LIMK1 are among the genes that are typically deleted in people with Williams syndrome. Studies suggest that deletion of LIMK1, GTF2I, GTF2IRD1, and perhaps other genes may help explain the characteristic difficulties with visual–spatial tasks. Additionally, there is evidence that the loss of several of these genes, including CLIP2, may contribute to the unique behavioral characteristics, learning disabilities, and other cognitive difficulties seen in Williams syndrome.^[

 Because of such genetic disturbance there is abnormal production of calcitonin & calcitonin gene related peptide. This peptide may play a major role in normal development & function of CNS (Bellugi et al, 1990, 1992)

First identified as a MR syndrome in 1961 (William Baran-Boyes & Lowe 1961). WS affects about 1in 7500 to 1 in 20,000 persons.

Many individuals with WS show pronounced weakness in perceptual & visual spatial functioning & relative strengths in expressive language. This sparing of linguistic functioning in the face of global & cognitive deficit is seen in many aspects of language including semantics & syntax (Bellugi, Marks, Bihrle & sabo, 1988).

Many researchers describe WS as pleasant affectionate, charming (Morris & Leonard, 1990)

Prosody & discursive abilities (narration, structurization), preliminary studies indicate that WS adolescents have relative perseverationof these skills. On narration, WS individuals were found to use prosody significantly more often than DS group.

Pragmatic skills are reported to be poor. They exhibit difficulty with conversation discourse skills such as Topic introduction, Maintenance, Turn Taking, & maintaining appropriate eye contact.

Charecteristics also include:

1)Facial Features-“elfin like”

2)Heart and blood vessel problems-The majority of individuals with this syndrome have some type of heart or blood vessel problem. Typically, there is narrowing in the aorta (producing supravalvular aortic stenosis SVAS), or narrowing in the pulmonary arteries.

3) Hypercalcemia (elevated blood calcium levels)

Some young children with Williams Syndrome have elevations in their blood calcium level. The true frequency and cause of this problem is unknown. When hypercalcemia is present, it can cause extreme irritability or "colic-like" symptoms.

4) Low birth-weight / low weight gain

Most  children  with  Williams Syndrome have a slightly lower birth-weight than their brothers or sisters. Slow weight gain, especially during the first several years of life, is also a common problem and many children are diagnosed as "failure to thrive". Adult stature is slightly smaller than average.

5) Feeding problems

Many infants and young children have feeding problems. These problems have been linked to low muscle tone, severe gag reflex, poor suck/swallow, tactile defensiveness etc. Feeding difficulties tend to resolve as the children get older.

6) Hyperacusis (sensitive hearing)

Children with Williams Syndrome often have more sensitive hearing than other children; Certain frequencies or noise levels can be painful an/or startling to the individual. This condition often improves with age.

7) Overly friendly (excessively social) personality

Individuals with Williams Syndrome have a very endearing personality. They have a unique strength in their expressive language skills, and are extremely polite. They are typically unafraid of strangers and show a greater interest in contact with adults than with their peers.

8)Developmental delay, learning disabilities and attention deficit

Most people with Williams Syndrome have some degree of intellectual handicap. Young children with Williams Syndrome often experience developmental delays; milestones such as walking, talking and toilet training are often achieved somewhat later than is considered normal. Distractibility is a common problem in mid-childhood, which appears to get better as the children get older.

Older children and adults with Williams Syndrome often demonstrate intellectual "strengths and weaknesses." There are some intellectual areas (such as speech, long term memory, and social skills) in which performance is quite strong, while other intellectual areas (such as fine motor and spatial relations) are significantly deficient.

There also appears to be a higher prevalence of left-handedness and left-eye dominance in those with Williams.^[8] Individuals with Williams syndrome also report higher anxiety levels as well as phobia development, which may be associated with hyperacusis.

The prognosis for patients with Williams syndrome varies depending on the severity of the person's intellectual disabilities and heart problems. With early diagnosis and prompt therapy, some patients are able to live independently once they become adults, while others may need lifelong support. There are many ways for patients to cope with their disabilities. Special education and occupational therapy has been shown to improve patients' work and school performance.

STUDY

Retelling a Script-Based Story: Do Children With and Without Language Impairments Focus on Script and Story Elements?

Denyse V. Hayward, Ronald B. Gillam, Phuong Lien

Journal of Speech, Language, and Hearing Research Vol.16 235-245 August 2007

AIM

The purpose of this study was to determine whether children with LI demonstrated a similar pattern of recall.

Result

Retells from both groups contained more obligatory elements and elements with high causal connectivity. However, groups differed on the specific elements included.

Children in the AM group appeared to utilize script and causal connectivity elements when retelling a script-based story.

Children in the LI group appeared to focus more on script elements than causal connectivity.

Fragile X Syndrome

Fragile X syndrome, or Martin-Bell syndrome, is a genetic syndrome which results in a spectrum of characteristic physical, intellectual, emotional and behavioural features which range from severe to mild in manifestation.

The syndrome is associated with the expansion of a single trinucleotide gene sequence (CGG) on the X chromosome, and results in a failure to express the FMR-1 protein which is required for normal neural development. There are four generally accepted forms of Fragile X syndrome which relate to the length of the repeated CGG sequence; Normal (29-31 CGG repeats), Premutation (55-200 CGG repeats), Full Mutation (more than 200 CGG repeats), and Intermediate or Gray Zone Alleles (40 - 60 repeats).^[1]

Martin and Bell in 1943, described a pedigree of X-linked mental disability, without considering the macroorchidism (larger testicles).^[2] In 1969 Chris and Weesam first sighted an unusual "marker X chromosome" in association with mental disability.^[3] In 1970 Frederick Hecht coined the term "fragile site".

Renpenning's syndrome is not synonymous with the syndrome. In Renpenning's syndrome, there is no fragile site on the X chromosome. Renpenning's cases have short stature, moderate microcephaly, and neurological (brain) disorders.

Escalante's syndrome is synonymous with the fragile X syndrome. This term has been used in Brazil and other South American countries.

Symptoms

Aside from intellectual disability, prominent characteristics of the syndrome include an elongated face, large or protruding ears, flat feet, larger testicles in men (macroorchidism), and low muscle tone. Speech may include cluttered speech or nervous speech^[7]. Behavioral characteristics may include stereotypic movements (e.g., hand-flapping) and atypical social development, particularly shyness and limited eye contact. Some individuals with the fragile X syndrome also meet the diagnostic criteria for autism. Most females who have the syndrome experience symptoms to a lesser degree because of their second X-chromosome, however they can develop just as severe symptoms. While full mutation males tend to present with severe intellectual disability, the symptoms of full mutation females run the gamut of minimally affected to severe intellectual disability, which may explain why females are underdiagnosed relative to males.

In short, similarities between X-linked recessive inheritance and fragile X are:

1.      Males are predominantly affected;

2.      Females (mothers) are obligatory carriers if a male child is affected, but not necessarily if female children are.

Differences are:

1.      Females may also have clinical symptoms.

Prominent characteristics of the syndrome include an elongated face, large or protruding ears, and low muscle tone.

Visual Oriention

Eye problems have not been found develop in accordance with mental age in individuals with fragile X. But patients with the syndrome have showed delayed voluntary orienting. The group differences in reflexive orienting between individuals with down and fragile X syndrome at the low mental age level reinforce the practice of separating etiologies and highlight the contribution of basic attentional processes in the study of people with mental retardation.

Ophthalmologic problems include strabismus (lazy eye). This requires early identification to avoid amblyopia. Surgery and/or patching are usually necessary to treat strabismus if diagnosed early. Refractive errors in patients with fragile X are also common.

Ø  It’s most common hereditary cause of moderate & severe MR.

Ø  It affects about 1 in 1000 persons (Shennan, 1992) results in wide range of learning & behavioral problems.

Ø  Individuals with Fragile X syndrome have null mutation of FMRI gene in which levels of protein in mRNA are greatly reduced. This is characterized at DNA level by abnormal repetition of CCG or CGG.

Ø  Some of the behavioral characteristics are:

o   Malesà majority of affected males can be placed in spectrum of anxiety, avoidance & gaze aversion. Many of the individuals have anxiety disorder (Bregmanetal, 1988)

o   Femalesà they also show certain emotional & behavioral problems. Some prpotion of women show scheizotypal disorder with salient symptoms involving difficulties in communication & social relation. Retardation ranges from mild to moderate.

o   APD problems are also reported. Attention, memory, auditory sequencing, word retrieval often affect both comprehension & production of speech & language.

For girls, many areas of speech and language may be strengths. Girls' verbal skills are generally good, with no particular disorders in speech (articulation), vocabulary (semantics), or grammar (syntax). Language disorders that may affect girls with fragile X syndrome are usually in the area of conversational skills (pragmatics).

Study

Communication in Young Children With Fragile X Syndrome: A Qualitative Study of Mothers' Perspectives

Nancy Brady, Debra Skinner, Joanne Roberts, Elizabeth Hennon
American Journal of Speech-Language Pathology Vol.15 353-364 November 2006

Aim

To provide descriptive and qualitative information about communication in young children with fragile X syndrome (FXS) and about how families react to and accommodate communication differences in their children.

Result

Over half the children were nonverbal and learning to communicate with augmentative and alternative communication

Mothers identified their roles as caregiver, teacher, therapist, and advocate

The perspectives offered by mothers are valuable because they indicate how children with FXS communicate in natural contexts.

Metabolic Disorders

It is estimated that nearly 30 diseases can be traced to inborn defects of metabolism & genes in parents that can be transmitted from one generation to another. Those causing MR are:

1) Phenylketonuria (PKU) à It is an inherted defect of aminoacid metabolism. At least 4 per 1,00,000 births are born with this defective metabolism. It’s characterized by inability of body to utilize essential Amino acid Phenylalanine. Phenylalanine builds up in the body fluids eventually divingurine a musty odorant ultimately causes irreversible brain damage. Unmetabolized amino acid interferes with process of myelination, sheathing of neuron axons. This sheathing is essential for rapid transmission of impulses & the neurons of frontal lobe are particularly affected.

2) Galactosemia à It is another metabolic disorder in which there is an inability to metabolize galactose due to the absence of an enzyme. Galactosemia is an inborn error of carbohydrate metabolism inherited as an autosomal redessive trait. It occurs approximately 1 in 40,000 to 60,000 birhts due to the faculty metabolism, there’s a damage to developing brain, liver, eye, & kidneys. If the condition is untreated, cataracts, Mental Retardation, etc may result.

3) Cretinism à This’ an inherited deficiency of thyroid gland function which if not treated early, results in progressive MR. Complete absence of thyroid glands, lethargy, irritability, anemia & retardation in physical growth are early symptoms of this condition.

study

Screening of Previously Undiagnosed Paediatric Cases

of Mental Retardation and Autism for Specific

Metabolic Disorders

CA Datar*, BN Apte**(2008)

Aim:To examine and investigate paediatric cases of mental

retardation and autism are presented. A large number of paediatric cases of mental retardation and autism where the exact cause cannot be ascertained after routine cytogenetic and molecular genetic investigations

Cases : A total of 37 cases (0-12 yrs) from special schools were examined. Cases were diagnosed

as having idiopathic mental retardation, autism or showed delay/regression of developmental

milestones.

Results

A conclusive diagnosis in 16 out of the 30 patients (54%). Of these 37% were

diagnosed as having one of the mucopolysaccharoidosis, 25% had homocystinuria, another 25%

had biotinidase deficiency. 12.5% cases had both homocystinuria and biotinidase deficiency.

Conclusion : From the above data it can be appreciated that, in 33% cases (cases of biotinidase

deficiency and homocystinuria), the disorder can be managed by metabolic intervention so as

to bring about some improvement in the severity of the symptoms

Early Language Development in Children with MR

The acquisition of language is one of the most remarkable achievements. Normally developing children would have acquired the essential components of language by about the age of 3 or 4.

Several distinct processing mechanisms form the foundation for the acquisition of language. Language acquisition is one of the most significant developments because it represents the integration of development in 3 domains; conceptual, linguistic & social. The child’s conceptual system which emerges in first year of life is the foundation on which the lexical & semantic developments are built. The more formal aspects of language which include the phonological or speech sound system & syntactic or grammatical system depend on separate computational mechanisms that are language specific. Finally, the pragmatic component or use of language as communicative system in different contexts builds on developments in the social domain. Each of these systems possesses different types of information from the environment. The conceptual system processes input about the physical world, the linguistic system operate on the input language & social system processes information about other persons.

Pre-linguistic Development

 The period of development covers the major part  of the first 18 months in the NR infant.The same development is extended in the moderately and severely MR child and occupies most of the first 2 or 3 years.during this period ,the child learns the basic principles of human  communicationfirst at the non verbal level ,later the child goes from a global mode of expression involving the whole or most of the body to more differentiated forms centering on vocal activity.the infants vocal activity modifies itself considerably during  prelinguistic development it goes from crying and cooing to babbling and later to production of conventional words.During the early phase of prelinguistic period there are distinct pattern of  development among groups of infants with retardation. 

a)vocal development:oller and his colleagues have shown that there are delays in the onset of canonical babbling in DS infanfs.(lynch ,oller Eilers,and Basinger1990,Oller and Siebert 1988,Steffens ,Oller ,Lynch ,and Vrbano 1992).

     Comparing infants with DS to a group of normally developing infants,the age of onset for infants with DS was about 2 months behind the normal groups.once canonical babbing began in DS ,it was significantly less stablethan for the normally developing infants. Lynch et al (1990)suggest this might be related to motor delays and hypotinicity that are characteristic of DS (Wishart 1988).thus infants with DS show specific patterns of delay in phonologic development,which in turn are correlated with later measures of communication functioning(Lynch et al 1990).these delays suggest that the biological mechanisms underlying the articulatory system and motor functioning may be especially vulnerable in DS .

b)social communicative development

In general young children with DS are much more sociable and show greater interest in people compared to young autistic children.

Infants with DS shows delays in the onset of :

Mutual eye contact(Berger and Cunningham 1988)

Vacalize much less (Berger and Cunningham 1988)

Their dyadic interaction with their mothers are less co-ordinated(Jasnow et al 1988)

By second half of first year infants with DS catch up ,then showing significantly higher levels of mutual eye contact with their care givers.

Much less published work exists on early pre linguistic development in other retarded population .males with fragile-x syndrome which co-occurs  with autism about 8% of the time (Brown et al 1986)are known to have poor eye contact ,which is charecterised primarily as gaze aversion.in contrast to fragile –x – syndrome young children with WS are extremely interested in human faces and spend extended periods of same looking intently at others face (Bellugi ,Bhirle ,Neville ,Jerningan ,and Doherty 1992).

2)Lexical Development :

Lexical development is markedly delayed in moderately and severely MR children.the first recognizable words are recorded between 30 months of age(Cunningham19,lambert and Rondal 1980).around 30 months (CA)the proportion of conventional words in the vocal productions of DS children is less than 5% (smith 77 ,smith and oller 1981)this figure gradually increases with age and around 4 years CA more numerous meaningful vocalizations are produced. Bless ,switt and Rosin (1985)reported vocabulary production and comprehension both delayed compared with non-verbal cognitive status in DS children(CA:5-8 years).

Mein and O’Connort(1960)reported that compared to NR subjects of similar mental ages , MR subjects have larger “core” vocabularies (i.e the set constituted by the words used by atleast half of the subjects in the sample)and smaller “fringe”vocabularies and as mental age increase ,the proportion of core words in total vocabulary decreases (Wolensberer,Mein ,and O ‘connort1963)and with increase in mental age ,the proportion of nouns produced by MR subjects decreases ,whereas proportion of other formal classes increases.

-overall MR and NR children seem to present similar patterns of early vocabulary development.Both groups acquire social words and a few object names first and later relational words and more object names(Gilliam 1979 ,Gopnik 1987).The object name vocabularies acquired by young DS children have referential contexts similar to those of NR children .(Cunningham and sloper 1984)

-Barett and Diniz (1989) in their review claim that lexical development in MR children soon starts to fail behind that of MA matched NR children.

Productive lexical use may be further delayed and hampered particularly in some MR children due to articulatory difficulties and memory limitations .this makes up for the dissociation sometimes observed between productive and receptive lexical capacity in MR subjects.(Miller 1988)

The differences in results (regarding normal /delayed patterns of lexical development )depends on matching variables considered by the authors.

e.g Cardoso –Martins et al (1985)observed that DS children have similar sized vocabularies both in production and in comprehension as NA matched NR children when MA is between 13-21 months .the same authors observed that DS children tend to have smaller vocabularies than NR children when matching variable if level of sensory motor development.

a)Lexical Definition:Lexical development appears to be reasonably well in line with MA in MR subjects.however ,this suggestion may not apply as well to lexical definition as an instance of metalexical ability.i.e the verbal product of conscious awareness of conventional meaning of words . In papania’s study (1954)mildly MR children varies various etiology (CA 9-16 yrs )produced fewer abstract and more concrete word definition MA matched NR children.

b)semantic lexical categories and networks:

              Longitudinal observation and cross sectional experimental studies by Mervis and her colleagues have confirmed that the children with DS and WS extend the meanings of words according to principle of extendability (Cardoso –martins et al 1985;Mervis  and akretrand 1997)children with MR will generalize new words ,attending word meanings to new examples .Even severely retarded non verbal children can acquire categorical knowledge following these same principles(Hupp and Mervis 1982).In case of other semantic lexical categories such as action names,adjectives,pronouns demonstratives and connectives less evidence is available.Bartel,Bryen and kechen (1973)have reported data concerning acquisition of action names,pronouns(he,she,they)demonstratives (this,that,these,those)and connectives.

Study

What Can Graph Theory Tell Us About Word Learning and Lexical Retrieval?

Michael .s.vitevitch Journal of Speech, Language, and Hearing Research Vol.51 408-422 April 2008.

AIM:Tools were applied to the mental lexicon to examine the organization of words in the lexicon and to explore how that structure might influence the acquisition and retrieval of phonological word-forms.

RESULT

The average path length and clustering coefficient suggest that the phonological network exhibits small-world characteristics.

The degree distribution was fit better by an exponential rather than a power-law function

The graph theoretic perspective may provide novel insights about the mental lexicon and lead to future studies that help us better understand language development and processing.

Morphosyntactic Development:

          Morphosyntactic development is slow and remains largely incomplete in moderately and severely grade MR subjects.The slowness and limitation of MLU development in moderate and severe MR subjects correspond to important shortcomings in morphosyntax.

  In young MR children ,the production of grammatical words is reduced (i.e articles ,prepositions ,pronouns, modals,auxiliaries and conjunctions ).This gives their utterances a telegraphic character (Brown ,1973).later,Fowler et al (1994) the proportions of pronouns ,prepositions ,modals, WH forms are similar in DS and MLU matched NR children.

DS children reach MLU  2 around 4-5 yrs CA ,MLU 3 around 7-8yrs ,and MLU 6 around 14 or 15 yrs.in comparison NR children reach MLU 5 or more around 6 yrs .the slowness and limitation of MLU development in moderately and severely MR childrencorrespond to incoming short comings in morphosyntax.

-Fowler et al (1994) supplied additional information on either grammatical morphological development in DS.he reported the rapid acquisition of plural form or nouns,prepositions ‘in’ and ‘on’ and the progressive form ‘ing’ .These are the same first four grammatical morphemes acquired by NR children around 30 months.

-chapman ,Schwartz (1992) observed  that older DS children and adolescents more frequently omit free and bound grammatical morphemes than MLU matched NR  controls in narrative speech sample.

There are numerous reports pointing to the research limitations of MR children and adolescents in the comprehension of morphosyntactic structures and their lagging behind MA matched NR contents in this respect as well.

Semmel and Dooley (1971) Berry (1972)chipman (1979)analysed the particular difficulties of mildly moderately and severely MR subjects in comprehension of grammatical words ,gender , and number agreement ,double object construction in English (e.g she gave the lady the baby),temporal relations between clauses and passive constructions.

Bellugi et al (1990) have documented a clear difference between their WS and DS subjects expressive language.The WS adolescent demonstrate larger MLU and more complex noun and verb phrases than DS subjects .their spontaneous speech contains full passives ,embedded relative clauses and conditional which are largely missing in speech of DS adolescents.

Studies of DS children suggest that majority of this population fit the pronominal profile. These children tend to rely heavily on pronouns and demonstratives (e.g referring to objects and people as it ,this  or he)and use relatively fewer nominal terms especially during early stages of language development(Dorrley 1976 ,singer et al 1994 ,Tager flusberg et al 1990).this reliance on pronouns and demonstrative rather than using more specific nouns may be due to memory limitations ,word finding difficulties or both .

Conclusion: At early stage of grammatical development ,studies suggest that children across a range of retardation syndromes acquire syntactic and morphological knowledge in same way and in same order as do normally developing children. Beyond early stages ,clear differences begin to emerge with some children in particular populations .For e.g children with autism and Williams syndrome acquire a grammatical system ,whereas other groups particularly children with DS show serious limitation in their grammatical development. The deficits in children with DS suggest that they may suffer specific impairment to the mechanism that serves to process linguistic information (Fowler 1990).

4) Pragmatic Development

a)Speech acts in children with MR :

Communication even in the pre-linguistic stages provide one of the key motivating factors for learning language.It appears that pragmatic development is closely tied to developments in childrens theory of mind particularly their mentalistic understanding of intentions and other mental states (locke 1993 ,tager flusberg 1993).

Bheegly et al (1990)found that children with DS  ,who were at early stages of language development with MLU  1.7 to 2.0 produced significant fewer requests than the mental age matched normally developing children.

b)conversational abilities :

Reilev klima and Bellugi (1991)compared cognitively matched WS and DS adolescents in a story telling activityand found that WS adolescents told coherent and complex narratives that made extensive use of prosody.WS subjects used more features such as effective and mental verbs emphatic and tense forms ,negative marker ,causal connectors etc.Despite their cognitive impairment ,subjects with WS are not able to deal with structural demands of narratives but also consciously to manipulate effective linguistic devices for the purpose of effective story telling.

Major change that takes place in development of conversational ability is in the capacity to maintain a topic over an increasing no of turns (Brown 1980 ,Bloom et al 1976)Beeghly et al (1990)found that their subjects with DS spent significantly more turns on the same topic than language matched controls.

-urly ,Tager Flusberg ,and Anderson (1991)found that children with DS were able to maintain a conversational topic at levels higher than normally developing children suggesting that their aspect of language is a genuine strength of this population. However ,they often lack language skills and relevant knowledge to advance topic(Warne and Bedrosion 1988)

-Fragile-x syndrome males have difficulties in maintaining a conversational topic.

-Loggins and Stoel Gammon (1982)found that even at early stages ,young children with DS are surprisingly good at conversational repairs ,they revise rather than repeating.

Young children with WS are also relatively good at conversation repairs (keiley and Tager Flusberg ,1994)

Conclusion: studies on pragmatic abilities have known that this is an area of strength in DS and probably also WS  at early stages .In Contrast ,from the beginning ,pragmatic abilities are significantly impaired both in autism and fragile- x-syndrome.

Study

Epilepsy & Mental Retardation Limited to Females: An Under-recognized Disorder

Ingrid E. Scheffer, Samantha J. Turner, Leanne M. Dibbens, Marta A. Bayly, Kathryn Friend

Brain (2008), 131, 918 – 927

AIM

Epilepsy and Mental Retardation limited to Females (EFMR) which links to Xq22 has been reported in only one family.

They aimed to determine if there was a distinctive phenotype that would enhance recognition of this disorder.

RESULT

Conclude that EFMR is a distinctive, under-recognized familial syndrome where girls present with convulsions in infancy, often associated with intellectual impairment and autistic features.

Clinical recognition is straightforward in multiplex families due to the unique inheritance pattern; however, this disorder should be considered in smaller families where females alone have seizures beginning in infancy, particularly in the setting of developmental delay.

In single cases, diagnosis will depend on identification of the molecular basis.

Speech development

It can be studied in terms of phonology. Phonology is the study of sound systems of language. Within phonology there are 2 branches; segmental & non-segmental phonology. Segmental phonology studies the way speech is analyzed into discrete segments along with the analysis of phonetic features & processes, which relate & differentiate these segments (Crystal, 1989).

Non-segmental phonology studies those features which extend over more than one segment such as intonation & rhythm.

Ø  Articulatory problems are more prevalent among MR subjects NR children. Prevalence varies with psychometric level of cognitive handicap & specific MR syndrome.

o   Mild MR subjects exhibit only a slightly higher incidence of articulatory difficulties (8 – 9%) than NR subjects.

o   Serious articulatory problems are seen in 70 – 90% of moderately & severely MR subjects.

Ø  DS subjects are particularly proved to slowness of articulatory development & persisting difficulties. A number of problems may be responsible for the high prevalence of speech difficulties in DS people. Peripheral pathologies associated with defective speech in DS has been observed (Benda 1949) which includes small buccal cavity for the tongue, protruding tongue (Ardan Barker & Kemp, 1972). Some DS children may have localized enlargement in the region of lingual tonsil, enlarged adenoids. A large proportion of the DS children show teeth deformities. These problems may result in defective dental occlusion & a change in the size of the oral cavity, which in turn may affect sound resonance. The palate may be short of cleft (Spitzer Bahowitch & Wybar 1961). The larynx is often laocated high in the neck with thickening of fibrotic mucosa, vocal fold oedema, myxoedema of larynx & an oedematous tongue which is impaired in its mobility. Hypotonia of speech muscles, involving tongue, lips, soft palate & breathing muscles is common.

Ø  Other factors influencing speech include auditory defects. Hearing loss is more frequent among MR subjects which is particularly true for DS individuals. The loss is from mild-moderate range. BERA in children with DS (Gigli et al 1984, Ferri et al 1986) confirm the existence of conductive losses in large proportion of subjects.

Ø  Deficits in motor coordination, timing & generalized hypotonia characteristic of DS subjects particularly during the first years may adversely affect the speech production system (O’Connor & Hermelin, 1963; Rosin, Swift & Bless, 1987). Deficits in motor coordination & timing may be partly responsible for the higher proportion of stuttering or stuttering like phenomena observed in moderately & severely MR subjects particularly DS subjects.

Ø  Voice problems are classically described as prominent in some MR subjects. The voice quality deviations often noted include breathiness, hoarseness & harshness. Some studies have reported higher fundamental frequency in DS individuals (Weinberg & Zlatin, 1970)

Ø  Benda (1949) suggested a relationship between specific vocal problems & anatomical-physiological features, frequent in DS. Many DS have small, blunt styloid processes as well as deviation of various other facial bones, these abnormalities may result in abnormal pull on larynx supporting be usual observation that larynx of DS subjects tend to be located higher in the neck than in normal. These abnormalities may favor deviations in voice quality.

b)Segmental Phonological Development

Articulatory development is slow & difficult in many MR children for a number of reasons including the delays & uncertainly of lexical development but the overall progression parallels that of NR children, even if many MR children (particularly DS children) exhibit more inconsistent articulation (Dodd, 1976; Smith & Oller, 1981; Dodd & Leahy, 1989; Borghi, 1990). Vowels, semivowels, nasals, & stop consonants are produced & mastered first. Fricatives /f/,  /s/,  /z/,  /S/,  /v/ & affricates /tò/,  /d  / are more difficult to articulate. They take longer to be mastered by MR subjects & may  never be achieved. The distinctive features found to be more error prone are the fricative-affricate, combined with the features of blade/alveolar, tip/dental, blade/prepalatal, & labio/dental. In DS, the anterior tongue appears to be particular associated with continuing faulty articulation (Stoel Gammon, 1980; Klink et al, 1986).

In contrast children with WS and autism do not appear to have particular problems with articulation. Gosh, stading and pankav 1994 studied large sample of WS subjects and found that their articulation was significantly better than mental age matched group of children with non specific retardation ,suggesting this as an area of particular strength for this population.

c)Non –Segmental Phonological Development:

         Non –Segmental features of babies babbling come to resemble prosodic patterns of mother tongue from as early as 6 months of age. A configuration of features is involved using primarily pitch ,rhythm and pause which gives prosodic envelops with recognizable intonation to the babies productions.

      Regarding prosody preliminary studies (Reily ,klima and kellugi 1991) (wing bellugi 1993)indicate that WS subjects have relative preservation of these skills on a Narration task,WS subjects were found to use prosody significantly more than DS group.they are able to establish clear intonation ,state the problem correctly ,introduce time and characters appropriately and clarify the resolution.

6)Types of problem behaviours (Gardner Williams):

                The retarded individual may exhibit too much behaviour in terms of general environmental requirements. In some instances the behaviour might not be inappropriate,the behaviour may be under poor environmental control concerning the place or frequency of its occurrence.

1)other factor that renders excessive behaviour patterns of particular concern to society is apparent self defeating character of such behaviour.It is difficult to understand what is accomplished by such behaviours.Thus there is a tendencyto view such behaviours as a result of some pathology .

2)Behavioural Deficit: The 2^nd class of problem behaviours are the behaviour,

which are absent in circumstances which require behaviours of a certain form.e.g. a retarded may not be able to read well enough to follow written directions and as a result fails in his vocational task or he may be unable to make the social response required for adjustment to group living conditions.

Relative nature of inadequacies

In viewing behavioral problems from the excessive deficit view point it is important to recognize that behavior is inherently inappropriate or inadequate. Behavior characteristics must be viewed as inappropriate or being of an excessive or deficit nature only in relation to the requirement imposed by a given environment.

Hence, it’s essential to recognize all these as important characteristics of behavior of retarded while developing educational & rehabilitation programs.

Categories of problem behavior

Various categories of deficits & excessive behavior have been identified & they include:

1)     Specific task skil deficit

2)     Task related deficit

3)     Deficits in independent living skills

4)     Social behavior deficits

5)     Affective behavior deficits

6)     Deficit in self directions & self control behavior.

7)     Excessive disruptive behavior

8)     Excessive social reactions

9)     Excessive motor reactions

10) Excessive affective reaction

Literacy characteristics of Educable MR (Malinda Dean Gorton)

Awareness of special charecteristics is important for us to help MR child. Left without help, he becomes lost & frustrated in completion with the usual children in school, work or play.

Educability: The most important & constructive characteristic of educable MR is the fact that he is capable of being educated & trained to maintain himself independently as an adult.

1)     Language limitations à

They speak in single words, the ‘me’ is center of everything. Sarasen explains that greatest difficulties for retarded are in use & comprehension of verbal & numerical symbols.

Prepositions are especially baffling. Children who do not respond readily to a direction may not understand, the meaning of a term used such as over, under, between or below.

Retarded child have difficulty blending sound into a word e.g., even though the child knows to spell “pan”. Though the child knows the sound of the beginning consonant “p” & the ending “an” he/she needs much help in associating & blending the sounds into a word.

2)     Lack of initiative for planning à

MR children are the followers of the world. Ingram states, “these children have less ability to learn from experience”. Sarason explains that judgement of subnormal as well as her creative ability is limited. When working with the retarded most teachers & parents have found that time id not understood nor is the value for planning. If teachers announce on Monday that class will have party on Friday their everyday all week, the party is topic of conversion with questions centering on “When is party”. So, the idea of the number & time must be understood to plan even a single party at school.

3)     United Imagination à

Educable MR tends to be practical. They seem to be unable to do work requiring originality. However, they are able to imitate & vary finished product with fanciful or playful additions. As child matures, he becomes more aware of his environment & his vocabulary imcreases. He is able to express his experiences in longer sentences & use a greater variety of words. Stories remain essential factual. TV & movie program are taken for truth usually.

4)     Limited use of concepts à

Educable MR are seldom able to distinguish between essential & non-essential factor in trying to solve personal or financial problem. Abstract terms are difficult to understand. In developing concepts, teachers should use simple language & also variety of demonstrations & experiences to ensure comprehension.

5)     Inability to evaluate efforts à

MR have little ability to evaluate their own efforts. The teacher should give deserved praise to strengthen confidence in their ability to perform designed tasks.

6)     Difficulty in distinguishing right from wrong à

Inability to distinguish right from wrong frequently causes MR to become involved in actions leading to juvenile court. Since children cannot generalize, teachers should teach certain factors like right or wrong.

7)cognitive deficits: one important problem in cognitive science is to understand the development of cognitive processes in children and to devise computer models to explore the mechanisms that underlie the changes.In particular,we are concerned with developmental changes in cognitive strategies in typical children and  in children with mild MR .Before the late 1950’s ,psychological theories of mental retardation were very global ,simply stating that individuals with MR failed to learn because they had low intelligence .philip vermon ,in the mid 1970’s pointed out that this view resulted in a circular explanation: to say that individuals with MR have difficulty learning because they have low intelligence adds nothing to the understanding of the nature of MR. To break the circularity of this global approach ,more specific theories of MR began to evolve.Most either focussed directly on the nature of memory deficiencies in individuals with MR or made memory a central component .In th early 1960’s, David zeaman and Betty house developed an attention-deficit theory of MR that localized the learning problem in attention. Norman Ellis identified the deficit in learning as a faulty short –term memory trace.Later ,John Belmont And Earl Butterfield attributed the locus of the learning Deficit to inadequate use of rehearsal strategies.

Research during the last 25 yrs has established deficiencies in three aspects of information processing in individuals with MR .At the very early stages of information processing ,individuals with MR do not process some basic aspects of visual stimuli in the same way as individuals with average intelligence do.

The second aspect of information processing that is deficient in individuals with MR is encoding ,which refers to the initial aspects of making information meaningful.

There are many studies which suggest that individuals with MR take longer to encode information and are less accurate in encoding information.For example ,from 1970-1985 at the university of Alabama in Tuscaloosa  ,Norman Ellis conducted a number of studies of short term memory.In one prototypical study ,participants were shown a single word and asked to recall it either immediately or during several retention intervals with delays of up to 30 seconds.Individuals with MR demonstrated consistently poorer recall than control subjects ,even on the immediate recall test.Further ,the magnitude of the difference at each retention interval was the same as the  difference observed on the immediate test. These findings led to the conclusion that information is forgotten at the same rate in both groups ,but that less information is encoded by the individuals with MR (an encoding deficit)