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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gender-related differences have consistently been reported in the language of adults and children with no disabilities. One well-replicated finding is that females discuss people and relationships more often than do males, particularly in conversations with other females. These stylistic variations in language are considered to have implications for the adaptive functioning of language users, most particularly females. Although studied thus far only in nondisabled individuals, such issues of language style use may be of equal or greater concern for those with mental retardation. How does a cognitive impairment intensify or reduce gender-linked language styles and their effects? Language transcripts were obtained from eight male and eight female participants with retardation, interacting separately with one male and one female adult partner. Half of the participants used speech as their primary mode of communication: the others relied on vocalization, gesture, or augmented modes. Participants using speech showed gender-linked language patterns similar to nondisabled individuals, with females discussing people significantly more often than males. Females using nonspeech modes, in contrast, showed a severe reduction in person-referencing that was not accountable by their expressive speech limitations.
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PMID:References to people in the communications of female and male youths with mental retardation. 965 99

Abnormalities in the muscle dystrophin-glycoprotein complex are implicated in the molecular pathogenesis of various neuromuscular disorders. Weakening of the trans-sarcolemmal linkage between the actin membrane-cytoskeleton and the extracellular matrix appears to trigger destabilization of the muscle cell periphery. In addition to muscular weakness, one-third of patients suffering from Duchenne muscular dystrophy exhibit mental retardation. Since little is known about the pathophysiology of brain abnormalities in these patients, we investigated the fate of the most abundant dystrophin-associated protein, beta-dystroglycan, in the central nervous system. It was found to be present throughout all normal brain regions studied. In contrast, this glycoprotein was greatly reduced in brain microsomes derived from Duchenne specimens, while it is of normal abundance in the brain from the dystrophic animal model mdx. Deficiency in brain beta-dystroglycan might render nervous tissue more susceptible to cellular disturbances and this may result in cognitive impairment in some Duchenne patients.
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PMID:Decreased expression of brain beta-dystroglycan in Duchenne muscular dystrophy but not in the mdx animal model. 970 63

Congenital ornithine transcarbamylase (OTC) deficiency is the most common inborn error of urea cycle enzymes in humans. A large percentage of survivors of neonatal OTC deficiency suffer severe developmental disorders, including seizures, mental retardation and cerebral palsy. Neuropathological studies reveal ventricular enlargement, cerebral atrophy and delayed myelination, as well as Alzheimer type II astrocytosis. Using the sparse-fur (spf) mouse model of congenital OTC deficiency, studies of central cholinergic integrity revealed a developmental delay in choline acetyltransferase activity and of high-affinity [3H]-choline uptake in several brain structures. Subsequent studies of muscarinic cholinergic binding site distribution showed a widespread loss of M1 sites, consistent with cholinergic cell loss. These alterations are similar to those reported in Alzheimer's disease, suggesting that the severe cognitive dysfunction in congenital OTC deficiency may at least partly result from a muscarinic cholinergic lesion. Possible mechanisms involved in the pathogenesis of cholinergic cell loss in congenital OTC deficiency include ammonia-induced inhibition of pyruvate and alpha-oxoglutarate oxidation, resulting in decreased synthesis of acetyl CoA and a cerebral energy deficit, as well as NMDA receptor-mediated excitotoxicity. Treatment of spf mice with acetyl-L-carnitine (ALCAR) results in partial recovery of the developmental choline acetyltransferase deficit, suggesting a potential therapeutic benefit of ALCAR in congenital OTC deficiency. Other therapies currently used include ammonia-lowering strategies (using sodium benzoate or sodium phenylacetate) and, in severe cases, liver transplantation.
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PMID:Evidence for a central cholinergic deficit in congenital ornithine transcarbamylase deficiency. 977 87

This study describes the clinical spectrum of patients with Klinefelter's syndrome and seizures. Klinefelter's syndrome is a sex chromosomal abnormality and the most common cause of male hypogonadism. It is characterized by cognitive dysfunction, hypogonadism, and abnormalities of physical maturation. Neurologic impairment has been recognized, but seizures have received little attention. The authors describe three American patients and discuss nine additional patients from two European centers previously reported with Klinefelter's syndrome and seizures. The most common profile of patients with Klinefelter's syndrome and seizures includes mental retardation, behavior problems, epileptiform electroencephalograms (EEGs), and generalized tonic-clonic seizures. The seizures of six of 11 patients with epilepsy were well controlled with antiepileptic drugs. One patient had a single seizure and was not treated with medication. In patients with Klinefelter's syndrome and recurrent seizures, the electroclinical spectrum is heterogenous and outcome with antiepileptic drug treatment is favorable.
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PMID:Seizures in Klinefelter's syndrome. 983 Sep 97

This review addresses the issues and challenges related to the differential diagnosis of autism in preschool children with significant cognitive impairment. Issues affecting differential diagnosis include the use of traditional diagnostic guidelines for preschoolers with developmental delays, developmental changes in behavioral characteristics, the involvement of cognitive factors in symptom expression, and the overlap between autism and mental retardation in individuals with significant cognitive impairment. The usefulness of autistic features for differential diagnosis is explored in terms of the core deficits of autism.
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PMID:Autistic features in young children with significant cognitive impairment: autism or mental retardation? 1042 86

We demonstrate here the importance of interleukin signalling pathways in cognitive function and the normal physiology of the CNS. Thorough investigation of an MRX critical region in Xp22.1-21.3 enabled us to identify a new gene expressed in brain that is responsible for a non-specific form of X-linked mental retardation. This gene encodes a 696 amino acid protein that has homology to IL-1 receptor accessory proteins. Non-overlapping deletions and a nonsense mutation in this gene were identified in patients with cognitive impairment only. Its high level of expression in post-natal brain structures involved in the hippocampal memory system suggests a specialized role for this new gene in the physiological processes underlying memory and learning abilities.
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PMID:A new member of the IL-1 receptor family highly expressed in hippocampus and involved in X-linked mental retardation. 1047 94

Down syndrome is caused by over-expression of genes located within a segment of chromosome 21, termed the Down locus. Down syndrome is associated with developmental abnormalities of the central nervous system that result in mental retardation and age-dependent Alzheimer-type neurodegeneration. Some of the neurodegenerative lesions, including A beta amyloid deposition, apoptotic cell death, and aberrant dendritic arborization, are in part due to constitutively increased expression of genes that encode the amyloid precursor protein, superoxide dismutase I, and S100-beta, and located within the Down locus. However, neurodegeneration in Down syndrome is also associated with aberrant expression of genes that are not linked to the Down locus, including the growth associated protein, GAP-43, nitric oxide synthase 3, neuronal thread protein, and pro-apoptosis genes such as p53, Bax, and interleukin-1 beta-converting enzyme. Increased expression of these non-Down locus genes correlates with proliferation of dystrophic neurites and apoptotic cell death, two important correlates of cognitive impairment in Alzheimer's disease. This article reviews the functional importance of abnormal gene expression in relation to Alzheimer-type neurodegeneration in brains of individuals with Down syndrome.
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PMID:Molecular abnormalities of the brain in Down syndrome: relevance to Alzheimer's neurodegeneration. 1066 65

Congenital ornithine transcarbamylase (OTC) deficiency in humans results in failure to thrive, hypotonia, seizures and mental retardation. Neuropathologic evaluation reveals significant cerebral cortical atrophy, delayed myelination and Alzheimer type II astrocytosis. Using an animal model of congenital OTC deficiency, the sparse fur (spf) mouse, studies reveal convincing evidence of a loss of forebrain cholinergic neurons in this condition. Evidence includes (i) reduced activities of the cholinergic nerve terminal enzyme choline acetyltransferase (ChAT), (ii) a 25% loss of ChAT immunostaining, (iii) reduced high affinity transport of [3H]choline by cortical synaptosomes and (iv) a selective reduction in densities of presynaptic muscarinic M2 binding sites, in spf mouse brain compared to controls. A partial correction of the cholinergic deficit was observed following treatment with acetyl-L-carnitine. Possible mechanisms responsible for cholinergic neuronal loss in congenital OTC deficiency include decreased synthesis of the ChAT substrate acetyl CoA, impaired cerebral energy metabolism and NMDA receptor-mediated excitotoxicity. Loss of forebrain cholinergic neurons is consistent with the severe cognitive impairment characteristic of congenital OTC deficiency.
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PMID:Evidence for forebrain cholinergic neuronal loss in congenital ornithine transcarbamylase deficiency. 1088 42

The Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS), a neurodevelopmental tool for the cognitive assessment of infants and toddlers, correlates well with the Bayley Scales of Infant Development. In 1993 the Bayley Scales were revised and the second edition published (BSID-II). This study was designed to determine how well the CAT/CLAMS correlates with the BSID-II and its utility in identifying mild and severe cognitive impairment. Sixty-eight infants and toddlers (age range = 14-48 months), referred for suspected developmental delays, were administered the CAT/CLAMS and BSID-II and the results compared. The correlation between the two instruments was strong (r = 0.89, P<0.0001). The CAT/CLAMS was sensitive (81%) and specific (85%) for detecting overall cognitive impairment (BSID-II less than 70) and was even more sensitive (100%) and specific (96%) in detecting severe cognitive impairment (BSID-II less than 50). The physician using the CAT/CLAMS formulated a clinical impression of cognitive impairment that was sensitive (95%) and specific (84%) compared with formal psychologic testing. The CAT/CLAMS correlates well with the BSID-II. It is useful for detecting and quantifying mild and severe cognitive impairment. It permits the physician to formulate an accurate clinical impression of cognitive impairment consistent with possible mental retardation.
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PMID:CAT/CLAMS: its use in detecting early childhood cognitive impairment. 1103 82

Mucopolysaccharidosis type VII (MPS VII) is a lysosomal storage disease caused by the lack of beta-glucuronidase (GUSB) activity. GUSB deficiency leads to the progressive accumulation of undegraded glycosaminoglycans (GAGs) in cells of most tissues, including the brain, and is associated with mental retardation. Reduction of lysosomal storage in the central nervous system and prevention of cognitive dysfunction may require intracranial delivery of a therapeutic agent during the newborn period that provides a continuous source of GUSB. Therefore, we injected recombinant adeno-associated virus encoding human GUSB into both the anterior cortex and the hippocampus of newborn MPS VII mice. Total GUSB activity in the brain approached normal levels by 18 weeks. Although GUSB activity was concentrated near the injection sites, lysosomal distension was reduced in most areas of the brain. In addition to histopathologic evidence of GAG reduction, the previously undescribed accumulation of GM2 and GM3 gangliosides in the brain was also prevented. Furthermore, GUSB expression and reduced lysosomal distension correlated with improvements in cognitive function as measured in the Morris Water Maze test. These findings indicate that localized overexpression of GUSB has positive effects on the pathology and cognitive function and does not have overt toxicity.
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PMID:Intracranial injection of recombinant adeno-associated virus improves cognitive function in a murine model of mucopolysaccharidosis type VII. 1127 77


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