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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The neuropsychological study of 50 children with the diagnosis of mental retardation permitted to devide them into 2 groups according to the character and severity of disturbances. In the first group disturbances of some cortical functions are of a dynamical character, in the second group there is a stable insufficiency. The prevalence of the defect is different: in the first group phenomena of a dysfunction are observed in the zone of verbal tasks and in the second--in the verbal and nonverbal areas. The consideration of these results from the point of view of the conjugate brain activity allows one to state in the first group a dysfunction of the left (speech) hemisphere along with the normal development of the right hemisphere. In the second group there is a dysfunction of both hemispheres which points to a more expressed severity of disturbances. A special neuropsychological study of the functions of the frontal lobes protecting the highest forms of behaviour regulation demonstrates their different insufficiency in children with mental retardation. The first group shows impulsiveness and instability of an arbitrary control, the second group--enertness, perseveration in programming movements and actions. However, the anomaly of mental development in the second group of children may be related to mental retardation, since the marked defects are compensated by the possibility of holding intentions and capability of purposeful activity.
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PMID:[Neuropsychologic characteristics of children with retarded mental development]. 60 62

The present study was designed to provide further information on the enduring cognitive effects of experimental phenylketonuria (PKU) in rats, produced by the administration of alpha-methylphenylalanine and phenylalanine on postnatal days 3-21. These rats evidenced: (1) impaired learning set formation, (2) stimulus perseveration, particularly after an error, and (3) difficulty in utilizing the less salient features of their environment in mastering discrimination problems. In contrast, long-term memory function and the ability to form simple associations did not differ from controls. This pattern of intact and impaired cognitive functions bears remarkable similarity to that of mentally retarded humans and neonatally hyperphenylalaninemic rhesus monkeys, thus affirming the use of rats to study mental retardation. In addition, possible reasons for the mildness of the impairments commonly observed in animal models of severe mental retardation syndromes are discussed. We suggest that transfer of learning paradigms that assess the animal's ability to use information acquired in other problems are more likely to uncover significant cognitive impairments in such models than are procedures that test only the animals' ability to solve a single problem.
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PMID:Cognitive profile of rats exposed to lactational hyperphenylalaninemia: correspondence with human mental retardation. 237 59

Autism is a behaviorally defined, life-long static developmental disorder of the brain that is poised for neurobiological investigation. It affects at least 1 or 2 in 1000 persons and has a broad range of severity. It has multiple causes, with genetics playing a major role. According to the DSM-IV, defining features are impaired sociability, language and communication, and range of interests and activities. Mental deficiency is frequent but by no means universal. The cognitive profile is characteristic, occasionally with a superior but narrow talent. Perseveration, concreteness, affective blunting, and lack of insight into other persons' thinking may be conspicuous. The neurological basis of autism's many sensorimotor features, including stereotypies, is unknown. Attention and sleep are affected, and one third of individuals experience epilepsy by adulthood. Whether subclinical epilepsy plays a role in the developmental regression of the one third of the toddlers who lose their language skills and become autistic remains to be determined. Clinical neuroimaging and biochemical investigations are generally unremarkable. Fewer than 35 brains have been examined pathologically, none with modern techniques. The findings thus far suggest subtle prenatal neuronal maldevelopment in the cerebellum and certain limbic structures. Abnormalities in distributed networks involving serotonin and perhaps other neurotransmitters require further documentation.
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PMID:Neurobiology of autism. 945 Jul 63

The utility of the Dementia Rating Scale (DRS) when administered to individuals with mental retardation (MR) was examined. Our sample was comprised of individuals residing in an intermediate care facility in the southeastern United States, included individuals diagnosed with mild, moderate, or severe MR, and consisted of both Caucasians (50%) and individuals of African-American descent (50%). Descriptive statistics for the DRS Total Score and five subtests (e. g., Attention, Initiation/Perseveration, Construction, Conceptualization, and Memory) obtained from our sample of individuals with mild MR compared favorably with previously published values. The group with mild MR performed significantly better than the group with moderate MR on the Total Score and all subtests except Construction, and the group with moderate MR performed significantly better than individuals with severe MR on all measures. These results show that the DRS can provide information about the cognitive strengths and weaknesses of individuals with mental retardation, and they show that the DRS can be administered to a wide range of individuals diagnosed with MR.
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PMID:Further support for using the dementia rating scale in the assessment of neuro-cognitive functions of individuals with mental retardation. 1085 61