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PubMedDate not supplied

Qualitative assessment of brain anomalies in adolescents with mental retardation.

BACKGROUND AND PURPOSE: The neural basis of mental retardation is poorly understood. This study aimed to characterize structural anomalies of the brain in mental retardation and the relationship between them and the degree of mental retardation. METHODS: Eighty adolescents receiving educational support and 40 controls underwent MR brain imaging and intelligence quotient (IQ) assessment. MR images were evaluated according to a checklist of qualitative brain anomalies by a neuroradiologist blind to group membership. All scans were assessed by a second neuroradiologist to measure interobserver agreement. Ten percent of the studies were randomly selected for assessment of intraobserver agreement. RESULTS: Evaluation of MR images by using the checklist generated results with a high degree of interobserver and intraobserver agreement. Intraclass correlations were 0.93 and 0.75 for interobserver agreement on the total abnormality score and the entire checklist, respectively, and 0.97 and 0.85 for intraobserver agreement on the total abnormality score and the entire checklist, respectively. IQ is negatively correlated with the total abnormality score (P < .001). Subjects with an IQ <70 have a significantly greater total score (P = .003) and a significantly greater score for 12 specific anomalies, including thinning of the corpus callosum (P = .001) and abnormalities of the lateral ventricles. CONCLUSION: Mental retardation is associated with demonstrable brain anomalies, particularly thinning of the corpus callosum and ventricular abnormalities, and with a high total abnormality score. Greater levels of brain anomalies are associated with greater levels of mental retardation as evidenced by IQ.

Adolescent↗
PubMed1977

Prevention of mental retardation: the role of medicine.

In the past 100 years striking progress has been made in the prevention of mental retardation. Since mental retardation is a symptom rather than a distinct disease entity, its prevention requires attention to many different areas. Heterozygote detection, specific factors of pregnancy, the current status of newborn screening, and major postnatal factors associated with mental retardation are some of the issues discussed in this centennial paper. Although considerable progress has been made, the causes and, hence, the modes of prevention of mental retardation for the majority of retarded individuals are unknown. Continued progress will require the combined efforts of both medical and social scientists if the goal, the prevention of mental retardation, is to be realized.

Abnormalities, Drug-Induced↗
PubMed1991

Consanguinity and mental retardation.

Consanguinity among parents as a cause of mental retardation in their children is debatable. The present study was conducted to find out the effect of consanguinity on mental retardation where the causative factor is not established. A total of 517 mentally retarded persons and their families were studied out of which 160 were born of consanguineous marriage and 357 were of non-consanguineous marriage. The results indicated that, when there is a history of mental retardation in the family and if the parents are consanguineously married, the risk of mental retardation in the offspring is significantly high (chi 2 = 11.52; P less than 0.001). Among the consanguineously married families, the blood relationship of uncle-niece seems to have the highest risk of affecting the offsprings. The implications are discussed in detail.

Adolescent↗
PubMed1992

[Mental retardation in children. Prevalence and etiology].

The prevalence of mental retardation defined as IQ less than 70 has been estimated as ranging between 6.7-11.9 per thousand children in the Nordic countries. Etiological factors can be found in 80% of patients with severe mental retardation (IQ less than 50) and in 50% with mild mental retardation (IQ 50-70). Down's syndrome is the most common specific cause of mental retardation, followed by the Fragile X syndrome, which mainly affects boys. Since the middle of the 1980s Rett's syndrome has been recognized as the most frequent cause of progressive mental retardation in girls. Recent advances in the field of chromosomal disorders, metabolic diseases and clinical syndromes imply a need for new epidemiological research aimed at obtaining an updated picture of the heterogenous causes of mental retardation.

Adolescent↗
PubMed1983

Sleep pattern in children with intractable epilepsy and mental retardation.

Four cases with intractable epilepsy and mental retardation (Epi + MR), four cases of mental retardation (MR), one case of mental retardation without epileptic seizures for the last several years (MR + (Epi] and two normal children were studied on their sleep pattern. Besides these, two cases of epilepsy (Epi) were examined. Awake time increased in the Epi + MR group. Slow wave sleep decreased markedly in the Epi + MR group. REM sleep decreased in the MR + (Epi) and Epi + MR groups. REM density was lowered in the following order: normal----Epi----MR----Epi + MR groups. The difference of sleep pattern among the normal, Epi and MR groups was not exhibited clearly, but severe sleep disturbances were shown in the Epi + MR group, implicating the severe brain dysfunction in the cortex and the brain stem.

Adolescent↗
PubMed1986

Psychiatric aspects of assessment of competence of mentally retarded persons.

There are some mentally retarded, developmentally handicapped persons who--if given an appropriate, enriched, and stimulating environment--can grow, mature, and develop cognitive abilities, emotional stability, and social skills to such a degree that they may become mentally competent, capable of assuming greater responsibilities, and move away from an institution to a more dignified environment in the community, where they may be treated and have, in many ways, the same rights as any other citizens. The role of the psychiatrist is to participate in this developmental process and to give his or her opinion as to the mentally retarded person's mental capacity to live independently.

Adaptation, Psychological↗
PubMed1995

The priority of separable perception in stimulus classifications of children with mental retardation.

Children (mean CA = 12 years) with mental retardation and adults without mental retardation classified tetrads of stimuli that could be grouped according to identities on separate dimensions or according to overall similarity. When color, size, and line orientation were varied (Experiment 1), both groups used separate dimensions for classification. When hue, saturation, and brightness varied (Experiment 2), both groups used overall similarity for classification. Test-retest correlations showed that the predominant classifications were reliable across 1-week testing intervals. Results support Garner's distinction between separable and integral stimulus structure but do not support an integral-to-separable shift in perceptual development. Comparisons of the tetrad task used in the present study and triads used in previous work are discussed as well as implications of the present data for developmental theories of perceptual classification and processing in children with mental retardation.

Adolescent↗
PubMed2000

[Medical care and support for children with mental retardation in school].

Development of medical knowledge and technology has greatly improved our understanding of mental retardation. However, clinically applicable treatment of mental retardation is still limited. As described in the definition of mental retardation by the American Association of Mental Retardation, functional maladaptations in various aspects of everyday life are the most integral part of disabilities in mental retardation. The role of pediatric neurologist in the medical care for children with mental retardation is not limited in medical treatment. Pediatric neurologists should play an important role as a coordinators in integrated care. Providing of medical care in special schools for children with mental retardation is among the most important issues, since children spend most of their time either at home or in school. The current situation of "medical care" in school, and its problems are discussed.

Child↗
PubMed1990

The life expectancy of profoundly handicapped people with mental retardation.

BACKGROUND: The life expectancy of people with mental retardation is shorter than that of the general population. Exact estimates of the length of survival for mentally retarded persons at especially high risk are not available, however. METHODS: We collected data on mortality and other factors for 99,543 persons with developmental disabilities, including mental retardation, who received services from the California Department of Developmental Services between March 1984 and October 1987. Three subgroups were selected on the basis of the four characteristics identified in previous studies as the best predictors of mortality among mentally retarded people (deficits in cognitive function, limitations on mobility, incontinence, and inability to eat without assistance). In all three subgroups, the subjects had severe deficits in cognitive function and were incontinent; the subjects in subgroup 1 (n = 1550) were immobile and required tube feeding; those in subgroup 2 (n = 4513) were immobile but could eat with assistance; those in subgroup 3 (n = 997) were mobile (but not ambulatory) and could eat with assistance. Life tables were generated for each of the three subgroups. RESULTS: Immobile subjects were found to have a much shorter life expectancy than those who could move about. Those who also required tube feeding (subgroup 1) had a very short life expectancy (i.e., four to five additional years). Those who could eat if fed by others (subgroup 2) had an average life expectancy of approximately eight additional years. In contrast, those who were mobile though not ambulatory (subgroup 3) had a life expectancy of about 23 additional years. CONCLUSIONS: Severe mental retardation is associated with a decrease in life expectancy, particularly for those who were immobile.

Activities of Daily Living↗
PubMedDate not supplied

Nonambulatory persons with profound mental retardation: physical, developmental, and behavioral characteristics.

Although profound mental retardation is generally associated with various organic etiologies that result in substantial cognitive and behavioral deficits, little is known about specific subgroups of persons with profound mental retardation. This study presents data on the physical, developmental, and behavioral characteristics of a group of 203 nonambulatory persons with profound mental retardation residing within a specialized service setting. The results indicate that nonambulatory persons with profound mental retardation have a high prevalence of physical and medical problems along with high rates of self-injurious, stereotypic, and aggressive behavior. Assessment results from the Stanford-Binet (L-M), Bayley Scales of Infant Development-Mental Scale, and Vineland Adaptive Behavior Scale reveal a high degree of variability in cognitive and adaptive functioning. However, developmental age-equivalent scores of cognitive ability, communication, daily living, socialization, and motor skills for the group fell below the 1-year level. The data illustrate the complexity of needs in providing habilitative services to nonambulatory persons with profound mental retardation.

Activities of Daily Living↗
PubMed2003

Is mental retardation a defect of synapse structure and function?

Mental retardation is believed to be a result of alterations in molecular pathways underlying neuronal processes involved in cognitive functions. It is not fully understood, however, which molecular pathways are critical for cognitive mechanisms. Furthermore, whether mental retardation is a developmental or ongoing disorder of cognitive functions is unknown. Answering these questions will help elucidate the etiology of mental retardation and possibly lead to new therapies. Several recently published studies suggested that mental retardation might be caused by defects in synapse structure and function. Four genes mutated in families with mental retardation encode proteins known as Rho guanine nucleotide exchange factor 6, oligophrenin-1, p21-activated kinase, and guanine dissociation inhibitor 1. Each of these interacts with various guanine nucleotide-binding proteins involved in signaling pathways that regulate the actin cytoskeleton, neurite outgrowth, neurotransmitter release, and dendritic spine morphology. The goal is to understand the roles of these genes in normal cognitive functions.

Animals↗
PubMed2002

Abnormal expression of the KLF8 (ZNF741) gene in a female patient with an X;autosome translocation t(X;21)(p11.2;q22.3) and non-syndromic mental retardation.

Non-syndromic X linked mental retardation (MRX) is a heterogeneous group of conditions in which all patients have mental retardation as the only constant phenotypic feature. We have identified a female patient with mental retardation and a balanced translocation involving chromosomes X and 21, t(X;21)(p11.2;q22.3). Physical mapping of the translocation breakpoint on the human X chromosome was performed using fluorescence in situ hybridisation. We have mapped the X chromosome breakpoint to a 21 kb DNA fragment upstream of the first exon of the KLF8 (ZNF741) gene in Xp11.21. We have subsequently shown that the KLF8 transcript is no longer detected in cells from the patient, although KLF8 expression is otherwise normally present in control lymphoblasts. Mutation screening of probands from 20 unrelated XLMR families linked to the proximal short arm of the human X chromosome failed to show any mutation in the coding region of the KLF8 gene.

Child, Preschool↗
PubMed1990

Training nonverbal and verbal play skills to mentally retarded and autistic children.

Two mentally retarded boys with autism and one mentally retarded girl with Down syndrome were taught to initiate and play a ball game with an adult confederate. The program targeted both nonverbal responses related to the actual execution of the ball game as well as verbal responses for play initiation and providing compliments for the confederate's behavior. Training sessions provided ample practice in all aspects of the game from initiation to termination through use of brief play cycles. Instruction was provided using a combination of physical and verbal prompts as well as reinforcement and time-out. All three children learned the game and by the study's completion executed multiple play cycles each session. The implications of combining play and social skills training in programming for developmentally handicapped children are discussed.

Autistic Disorder↗
PubMed1999

Subtle chromosomal rearrangements in children with unexplained mental retardation.

BACKGROUND: No explanation for moderate to severe mental retardation is apparent in about 40% of cases. Although small chromosomal rearrangements may account for some undiagnosed cases, a lack of genome-wide screening methods has made it impossible to ascertain the frequency of such abnormalities. METHODS: A fluorescence in-situ hybridisation (FISH) test was used to examine the integrity of chromosome ends in 284 children with unexplained moderate to severe retardation, and in 182 children with unexplained mild retardation. 75 normal men were also tested. When a chromosomal rearrangement was found, its size was estimated, and members of the child's family were investigated. FINDINGS: Subtle chromosomal abnormalities occurred with a frequency of 7.4% in the children with moderate to severe mental retardation, and of 0.5% in the children with mild retardation. The abnormalities had an estimated population prevalence of 2.1 per 10,000, and were familial in almost half of cases. INTERPRETATION: Once recognisable syndromes have been excluded, abnormalities that include the ends of chromosomes are the commonest cause of mental retardation in children with undiagnosed moderate to severe mental retardation. Owing to the high prevalence of familial cases, screening for subtle chromosomal rearrangements is warranted in children with unexplained moderate to severe mental retardation.

Adolescent↗
PubMed1963

SKELETAL AGE IN SUBJECTS WITH MENTAL RETARDATION.

Delayed skeletal maturation has been long accepted as a correlate of mental retardation. Three hundred mentally retarded children were examined for skeletal age and failed to show any overall delay of bone age as compared to chronological age. Further, birth weight was found to be unrelated to bone age maturity. Children with severe levels of retardation displayed significant delay in bone development only when profound physical disability was also present. In eight diagnostic categories of mental retardation, only those with metabolic syndromes showed any significant delay in skeletal system maturation. Conversely, mongoloid children showed a larger-than-chance percentage of advanced bone maturation. Skeletal measures therefore are perhaps more reflective of etiological states than of diagnostic classifications in mental retardation.

Age Determination by Skeleton↗
PubMed1995

Auditory and visual evoked potentials in individuals with organic and cultural-familial mental retardation.

Brainstem, middle-latency, and long-latency auditory evoked potentials (BAEPs, MAEPs, and LAEPs) and visual evoked potentials (VEPs) were recorded from subjects without mental retardation (control subjects) and from subjects with organic mental retardation or cultural-familial mental retardation. Both mentally retarded groups had smaller mean VEP amplitudes and longer mean LAEP latencies in response to target stimuli than did the control subjects, showing that the target stimuli were evaluated more slowly by the subjects with than by those without mental retardation. We found no significant differences between the mentally retarded and control groups with regard to BAEPs or MAEPs, and the two mentally retarded groups did not differ significantly in any EP parameter. The implications of these results for the defect and developmental theories of mental retardation were discussed.

Adolescent↗
PubMed1992

Sentence processing by adolescents with and without mental retardation.

A more thorough test of the hypothesis that persons with mental retardation are less likely to construct semantically integrated representations of sentences that they hear than are subjects without mental retardation (Merrill & Bilsky, 1989; Merrill & Mar, 1987) was provided. A series of sentences were presented to adolescents with and without mental retardation. Their memory for the object nouns of the sentences was then tested when they were provided with either the subject noun, the verb, or the subject plus verb of the sentence as a retrieval cue. The two-word cue was relatively better if an integrated semantic representation was constructed. Manipulations included decreasing the processing time given to subjects (expected to inhibit the construction of integrated representations) and presenting a picture with the sentence (expected to facilitate the construction of integrated representations). The reduction in time decreased performance for the subjects without mental retardation to the level normally observed for those with mental retardation; presenting a picture increased performance of subjects with mental retardation to the level of comparison subjects. Results support the suggestion that previously observed differences in sentence processing between individuals with and without mental retardation may be due to differences in generating integrated representations of the sentences during processing.

Adolescent↗
PubMed1977

The aetiology of mental retardation.

The aetiological factors related to mental retardation are tabulated and discussed. The data comprise part of the findings of a large scale sociological survey of mental retardation and show that approximately 65% of subjects classified as "mentally retarded" have a specific diagnosis.

Adolescent↗