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BACKGROUND: People with mental retardation have limited access to oral health care. Dental school administrators reported minimal training in U.S. dental schools for these patients. As a result, students and practitioners may not be prepared to provide needed services. METHODS: The authors surveyed 295 third- and fourth-year students at five dental schools about their didactic and clinical preparation for, attitudes toward and comfort levels with treating people with mental retardation, as well as whether their experiences affect their willingness to treat people with mental retardation. The authors analyzed data using previously developed statistical software. RESULTS: A little more than 68 percent of respondents reported receiving five hours or less of instruction devoted to how to care for people with mental retardation, and 50.8 percent reported having no clinical training in this area. Nearly 60 percent reported that they had little to no confidence in providing care, while 74.6 percent reported they had little to no preparation in providing care. Students who had experience working with people with mental retardation attributed greater capabilities to such people than did students who had no such experience. CONCLUSIONS: Many U.S. dental students are prepared inadequately to provide services for people with mental retardation. Spending time with these patients provides a more positive understanding of the capabilities of these people. PRACTICE IMPLICATIONS: Increasing numbers of people with mental retardation no longer live in institutions, and they are dependent on dentists in private practice for care. Increased dental school training and continuing education programs are needed to meet this need.
INTRODUCTION: In the County of Copenhagen the treatment of mentally retarded (MR) children is centralised in the Center for Handicapped (CFH). The aim of this study was to elucidate whether the frequency of MR is higher in children from ethnic minorities than in the background population and whether an increase could be ascribed to inbreeding. MATERIAL AND METHODS: The medical records of children with a non-Danish family name and where both parents were from countries other than Denmark were studied. RESULTS: A significant increase in the frequency of MR were found in the children from ethnic minorities: 16.6% of the children seen at CFH had an ethnic background compared to 14% in the background population, making a surplus of 18.5% more than expected. When a family was inbred other family members had Mr in 43.0%, whereas more family members with MR were found in only 14.2% of the families with no inbreeding. In the consanguineous families we found possible aetiological diagnoses in 21.5% of the children compared to 49% in the non-consanguineous families. In the entire group of children from ethnic minorities, we found Down's syndrome in 3.2% compared to 10.7% in Danish children with MR. DISCUSSION: There is a surplus of MR in children from ethnic minorities in the County of Copenhagen. The causes are not known, nor are aetiological factors for MR for a great part of the children. Consanguinity is likely to be a risk factor for MR, especially if it is already present in the family. This conforms with previously published data from other countries.
The effects of cue-availability on short-term and long-term recall of 40 mentally retarded children were investigated. Subjects were chosen on the basis of comparable mental age (approximately 90 mo.) and randomly assigned to either an objects (high cues) group or slides (low cues) group. 52 familiar objects served as stimuli for the objects group and projected color photographs of the objects were presented to the slides group. In the short-term recall session the subjects were shown stimuli grouped into eight trials and asked to recall the names of the stimuli in each trial ten seconds after presentation. Delayed recall was obtained 48 hr. later in a free recall session. The objects group scored significantly higher than the slides group on memory span (p less than .01), short-term recall (p less than .001), and delayed recall (p less than .025). The facilitation of recall achieved by using three-dimensional stimuli was clearly demonstrated, and the relative degree of facilitation was comparable for both short- and long-term recall.
We report a moderately mentally retarded 7-year-old male with a unique combination of clinical symptoms and signs: severe pre- and postnatal growth retardation, scaling skin and quadrispasticity, hypospadias grade 2 and hydro-uretero nephrosis, postaxial polydactyly type B on the right hand. Normal fibroblast enzyme activities of fatty aldehyde dehydrogenase and NADPH cytochrome C reductase were not consistent with the diagnosis of Sjögren-Larsson syndrome. The nosology of 'bird-headed' dwarfism is briefly discussed.
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Risk factors for mental retardation were studied prospectively in 12 000 children born in northern Finland in 1966 and followed to the age of 14 years. The number of untraced children was less than 2 per 1000. Altogether 326 children had an IQ less than 86, and the incidence of severe retardation (IQ less than 50) was especially high. An incidence figure for children with mental retardation, a separate figure for healthy children, and also the death rate were calculated for each disease. Only in the cases of Down's syndrome and some hereditary diseases were all the exposed children mentally retarded; in other diseases some children did not seem to suffer any sequelae. A risk factor could be found for 50.6% of the total number of children with mental retardation, the percentage decreasing from the severest to the mildest form (86.7%, 45.4%, and 30.9%). Some 9.4% of the healthy children and 77.7% of those who died had had one or more of these conditions. Prenatal conditions were most often associated with severe mental retardation (64%), and perinatal conditions with mild retardation, (IQ 50 to 70; 27%) and mental subnormality (IQ 71 to 85; 18%). Cases with no known risk factor were more common among boys than girls.
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The biological basis of mental retardation is poorly understood. Mental retardation is associated with an immature morphology of synaptic spines, structures involved in neurotransmission and memory processes, suggesting that mental retardation is due to a deficiency in neuronal network formation. Recently, several genes involved in X-linked mental retardation (MRX) have been cloned. Investigation of the roles of these genes in neuronal development and function should lead to a better understanding of the cellular mechanisms underlying mental retardation. A significant number of MRX genes is directly involved in signal transduction through Rho proteins. These Rho proteins act as molecular switches which integrate extracellular and intracellular signals to regulate rearrangement of the actin cytoskeleton. Since the actin cytoskeleton mediates neuronal motility and morphogenesis, one can envision how mutations in proteins involved in Rho-dependent signaling result in mental retardation by altering neuronal network formation.
X-linked mental retardation (XLMR) is an extremely heterogeneous condition that account for 15-25% of all mentally retarded patients. The number of genes newly reported in relation with this condition has been rapidly increased in the past years. One of the latest is called Jumonji AT-rich interactive domain 1C (JARID1C). This gene encodes for a member of a recently discovered protein family that harbours DNA-binding motifs, suggesting a possible role in transcriptional regulation and in the modification of chromatin structure. In this work we describe the results obtained by screening JARID1C gene in 24 mentally retarded males with history of at least two affected males. Remarkably, we have found a novel missense mutation in exon 10 of the gene that results in a Serine-to-arginine change at amino-acid 451 (S451R). This nucleotide change appears to be restricted to mentally retarded patients, since it has not been detected in control samples. Familial analysis has confirmed the segregation of this mutation with mental retardation. Furthermore, sequence alignment analysis with the different members of the human JARID1 family and with homologous proteins of mouse and fruit fly has revealed that the affected amino acid is conserved. Our data highlights the importance of reporting mutations in this gene since it might support the recent findings that implicates JARID1C with XLMR.
Prevention of mental retardation is discussed in terms of etiology and level of prevention (primary, secondary or tertiary). The aim of primary preventive medicine is to avert the disease before its onset. Secondary preventive medicine involves early identification and treatment of a disease to reduce its duration and/or severity. Tertiary prevention limits the degree of disability and fosters rehabilitation in chronic diseases. Prevention of mental retardation relies heavily on primary and secondary preventive techniques. Generally, preventive techniques related to organically caused mental retardation are secondary. Attempts are made to identify and treat impairments which cause deficient mental functioning. Since such impairments can occur at any time and are not always observable, routine developmental screening is recommended. A two-stage developmental screening procedure developed by the authors consists of an abbreviated version of the Denver Developmental Screening Test (DDST) followed by the full DDST when indicated. Primary preventive techniques are appropriate for the prevention of environmentally-caused mental retardation. If negative environmental influences can be identified and eliminated early, socio-cultural mental retardation might be averted or if identified early may be decreased to prevent the retardation process. To meet the need for an environmental screening instrument, the authors developed the Home Screening Questionnaire (HSQ). A combined developmental/environmental screening process is recommended.
30 mentally retarded deaf adolescents were matched with 30 mentally retarded hearing adolescents to evaluate (a) differences in creative thinking as a function of hearing status, (b) the effect of severity of mental retardation on hearing status, and (c) interaction between hearing status and intelligence. A multivariate factorial analysis of variance indicated that the mentally retarded deaf adolescents differed significantly from hearing adolescents on Fluency and Originality. The deaf youth scored higher on Fluency while the hearing scored higher on Originality. No other effects in the analysis reached significance.
Mental retardation is more common in males than females in the population, assumed to be due to mutations on the X chromosome. The prevalence of the 24 genes identified to date is low and less common than expansions in FMR1, which cause Fragile X syndrome. Systematic screening of all other X linked genes in X linked families with mental retardation is currently not feasible in a clinical setting. The phenotypes of genes causing syndromic and non-syndromic mental retardation (NLGN3, NLGN4, RPS6KA3(RSK2), OPHN1, ATRX, SLC6A8, ARX, SYN1, AGTR2, MECP2, PQBP1, SMCX, and SLC16A2) are first discussed, as these may be the focus of more targeted mutation analysis. Secondly, the relative prevalence of genes causing only non-syndromic mental retardation (IL1RAPL1, TM4SF2, ZNF41, FTSJ1, DLG3, FACL4, PAK3, ARHGEF6, FMR2, and GDI) is summarised. Thirdly, the problem of recurrence risk where a molecular genetics diagnosis has not been made and what proportion of the male excess of mental retardation is due to monogenic disorders of the X chromosome are discussed.
Mildly mentally retarded adults were compared on both an auditory and a visual vigilance task with subjects having greater than average intelligence. Contrary to results reported by Semmel (1965) using a visual task, no difference was found in the rate of decline of performance between the two groups in either of the two tasks, although overall performance of the above-average group was superior to that of the retarded group. The results offered no support for the hypothesis that mentally retarded persons suffer from a more rapid decay in arousal under conditions of reduced sensory variation. Nor did they support a suggestion that in this particular situation retarded subjects would demonstrate more inattention than would nonretarded subjects.
We assessed the present status of choice and usefulness of medical examinations of children with mental retardation (MR) and/or pervasive developmental disorder (PDD). Children with severe MR received more examinations than those with mild MR. Many abnormal findings were demonstrated by MRI in cases of severe MR. Cases of PDD without MR rarely showed abnormal results. Cases of PDD with MR underwent fewer examinations, but showed more abnormal results. We presented guidelines regarding medical examinations for children with MR in pediatric clinics which are specialized for developmental disorders, including psychological tests, hearing tests, EEG, genetic tests and neuroimaging. Physicians should select appropriate medical examinations based on evidence. The goal of testing is to provide useful information concerning medical treatment, therapeutic rearing, and education, and to support patients and their families in cooperation with relevant facilities.
X-linked mental retardation (XLMR) is a genetically and clinically heterogeneous common disorder. A cumulative frequency of about 1/600 male births was estimated by different authors, including the fragile X syndrome, which affects 1/4000 males. Given this very high cumulative frequency, identification of genes and molecular mechanisms involved in other XLMRs, represents a challenging task of considerable medical importance. In this report we describe clinical and molecular investigations in the family of a mentally retarded boy for whom a microdeletion in Xp21.3-22.1 was detected within the frame of a previously reported systematic search for deletion using STS-PCR screening. Thorough clinical investigation of the sibling showed that two affected brothers exhibit a moderate non-specific mental retardation without any additional neurological impairment, statural growth deficiency or characteristic dysmorphy. Molecular analysis revealed that the microdeletion observed in this family is an inherited defect which cosegregates with mental retardation as an X-linked recessive condition, since both non-deleted boys and transmitting mother are normal. These results and the inherited microdeletion detected within the same region associated with non-specific MR, reported by Raeymaekers et al., suggest that Xp21.3 MR locus is prone to deletions. Therefore, search for microdeletions in the eight families assigned by linkage analysis to this region might allow a better definition of the critical region and an identification of the gene involved in this X-linked mental retardation.