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

During development of the brain, many neurons exhibit a dependence on other neuronal populations for their survival and differentiation (target dependence). Evidence suggests that some neural pathways are much more dependent on single target neuronal populations for their survival than are others (differential target dependence). This phenomenon has important implications both for animal models of congenital human brain damage and for ideas concerning the aetiology of behavioural abnormalities associated with human mental retardation. Predictions of the neuronal deficits likely to arise from exposure to cytotoxic agents (e.g. ionizing radiation, hyperthermia, viral infection) at a particular time must take differential target dependence into account. It is known that target dependence affects corticopetal pathways involved with the discriminative senses (e.g. vision), more than monoaminergic and cholinergic corticopetal pathways which are believed to be involved with arousal, selective sensory attention, sleep, memory and cortical vasomotor function. Following prenatal damage to superficial layers of the cerebral cortex, this effect of differential target dependence leads not only to a relative hyperinnervation of the cortex with monoaminergic and cholinergic projections, but a specific deficit in visual pathways. The implications of this combined deficit for the behaviour and rehabilitation of the mentally retarded are considered.
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PMID:Differential target dependence in the developing brain: implications for mental retardation. 219 71

The first discovered exogenous teratogen causing mental retardation was rubella embryopathy described in 1940. Later, cytomegalic virus infection and toxoplasmosis during pregnancy and ionogenic radiation has been shown to cause embryofetopathies with concomitant mental retardation. Methyl mercury in high doses cause severe central nervous system pathology in both mothers and their fetuses. The fetal alcohol syndrome is now generally accepted as causing mostly mild mental retardation. Of therapeutic drugs, antiepileptics have been shown to carry a risk for the fetal antiepileptic syndrome complex. We have recently been able to describe fetal pathology following high intake of benzodiazepines during pregnancy.
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PMID:Prenatal factors including fetal alcohol syndrome. 289 25

The high incidence of hepatitis A and B in institutionalized patients with Down's syndrome is not fully understood. Under poor hygienic conditions immunological alterations might predispose to these infections. To minimize environmental influences, 125 patients with Down's syndrome (mean age 11.9 years) living at home with their families were studied for the occurrence of serological markers of Hepatitis A and B. 106 outpatients with mental retardation of other genesis (mean age 12.4 years), and 114 consecutive voluntary blood donors (mean age 18.0 years) from the same area served as controls. Evidence of previous hepatitis A virus infection was found in 5.6% of Down's patients, in 9.4% of other mentally retarded patients, and in 16.7% of healthy controls. Evidence of previous or ongoing hepatitis B virus infection was a common finding in both groups of mental retardation (Down's syndrome 20.0%, other mentally retarded patients 11.3%) in sharp contrast to healthy blood donors (0.9%, p less than 0.05). Patients with Down's syndrome, however, revealed a much higher incidence of HBs-antigenemia as compared with other mentally retarded patients (12.8% vs. 2.8%, p less than 0.01). All HBs antigen-positive cases had normal transaminase levels and no overt clinical signs of liver disease, suggesting an asymptomatic carrier state. These data indicate that hepatitis A is not a special risk for mentally retarded outpatients, while hepatitis B virus infection is hyperendemic even in not-institutionalized patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hepatitis A and B in non-institutionalized mentally retarded patients. 293 80

All types of central nervous system (CNS) infections were investigated in a 1966 birth cohort of 12,000 children from Northern Finland followed up from birth to the age of 14. 174 CNS infections occurred in 167 children, 110 boys and 64 girls. The annual incidence of bacterial CNS infections was 36.3/100,000 and that of viral infections 688.0/100 000. It is concluded that bacterial CNS infections were recorded very fully but only 2/3 of the viral infections could be traced, even though the more severe cases were quite well documented. 8/55 children (14.5%) with bacterial meningitis died; the corresponding figure for viral encephalitis and meningitis (excluding mumps) was 3/67 (4.5%). 17/55 (30.9%) developed mental retardation, epilepsy, cerebral palsy or hearing defect or some combination of these after bacterial CNS infection, and 9 (8.1%) after viral infection. The difference with respect to the children who had not experienced CNS infection was statistically significant only for the bacterial infection cases. CNS infections explained 7.6% of all deaths from 28 days to 14 years, 3% of the handicapping cases of cerebral palsy, mental retardation and epilepsy or some combination of these, and 6.6% of the hearing defects.
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PMID:Incidence and prognosis of central nervous system infections in a birth cohort of 12,000 children. 376 48

The prevalence of hepatitis B virus markers was determined in two residential institutions for the mentally disabled which exhibited major differences in operating policies. Eighty per cent of 91 clients and 16% of 92 employees at institution A had positive tests for hepatitis B virus markers, including two staff members and one client with serologic evidence of recent infection (immunoglobulin M antibody to hepatitis B core antigen). In contrast, 34% of 395 clients and 8% of 294 workers at institution B were positive for hepatitis B virus markers, and none of the staff demonstrated evidence of recent infection. The observed differences in seroprevalence were likely to have been influenced by substantial disparities in living conditions, staff-to-client ratios in critical areas, and level of employee experience. In addition to significant institutional differences, seroprevalence was associated with severity of mental retardation in clients and duration of employment in staff. This study emphasizes the importance of local policies in the prevention of hepatitis B virus infection at residential institutions for the mentally disabled.
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PMID:Different operating conditions affect risk of hepatitis B virus infection at two residential institutions for the mentally disabled. 395 48

A newborn baby presented with hyaline membrane disease, interstitial pneumonia, jaundice, hepatosplenomegaly, and unusual bone manifestations with lytic and sclerotic bone lesions and virtually absent periosteal reaction. He subsequently developed intracranial calcifications and mental retardation. The pneumonia and hepatosplenomegaly resolved. At the time of the delivery, a sibling was suffering from a severe undetermined viral infection. The clinical evolution of the disease and the radiologic findings led us to believe that this patient had a prenatal viral infection. The laboratory tests and the histologic picture of the bone biopsy supported the diagnosis.
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PMID:Unusual osteopathy in a newborn. 687 10

Over a 24 month period on six paediatric wards of different designs 169 cases of possible hospital-acquired respiratory virus infection were investigated. A variety of viruses was isolated from 82 cases, the most common being respiratory syncytial virus, influenza, parainfluenza, adenoviruses and rhinoviruses. A further 73 children developed respiratory symptoms between 3 and 300 days after administration but viruses were not demonstrable by the techniques used. These children were thought to have hospital-acquired infection nonetheless. Thirteen children were shown not to have acquired infection as the cause of their intercurrent illness. Most acquired infections occurred where toddlers were in cots in open wards. Children with trauma, including non-accidental injury, congenital malformations, mental retardation, failure to thrive or neoplasia were most likely to become infected. Almost 20% of children suffered from croup or lower respiratory tract illness as a result of their acquired infection. The figure was 41% if those less than 12 months old were considered alone. Most episodes settled quickly but in a few children investigations or surgery were delayed for a few days.
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PMID:A two year prospective study of hospital-acquired respiratory virus infection on paediatric wards. 724 Jul 35

Both genetic and environmental factors contribute to the pathogenesis of a wide variety of neurodevelopmental disorders, including autism, mental retardation, and schizophrenia. Some heritable disorders approach 100% penetrance; nonetheless, even in these disorders, subtle aspects of clinical disease expression may be influenced by the environment. In other disorders with genetic influences, exogenous factors, and the timepoint(s) during nervous system development at which they are introduced, modulate expression of disease. Elucidation of the mechanisms guiding this intricate interplay between host response genes, environmental agents, and the neurodevelopmental context within which these interactions occur, is necessary to understand the continuum of clinical outcomes. This chapter will review the evidence that infectious and immune factors may contribute to the pathogenesis of neurodevelopmental disorders, describe an animal model of neurodevelopmental disorders based upon viral infection, identify processes by which neural circuitry may be compromised, and outline areas for future research.
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PMID:Infectious and immune factors in the pathogenesis of neurodevelopmental disorders: epidemiology, hypotheses, and animal models. 1155 36

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection and mental retardation. HCMV infection, while causing asymptomatic infections in most immunocompetent subjects, can be transmitted during pregnancy from the mother with primary (and also recurrent) infection to the fetus. Hence, careful diagnosis of primary infection is required in the pregnant woman based on the most sensitive serologic assays (immunoglobulin M [IgM] and IgG avidity assays) and conventional virologic and molecular procedures for virus detection in blood. Maternal prognostic markers of fetal infection are still under investigation. If primary infection is diagnosed in a timely manner, prenatal diagnosis can be offered, including the search for virus and virus components in fetal blood and amniotic fluid, with fetal prognostic markers of HCMV disease still to be defined. However, the final step for definite diagnosis of congenital HCMV infection is detection of virus in the blood or urine in the first 1 to 2 weeks of life. To date, treatment of congenital infection with antiviral drugs is only palliative both prior to and after birth, whereas the only efficacious preventive measure seems to be the development of a safe and immunogenic vaccine, including recombinant, subunit, DNA, and peptide-based vaccines now under investigation. The following controversial issues are discussed in the light of the most recent advances in the field: the actual perception of the problem; universal serologic screening before pregnancy; the impact of correct counseling on decision making by the couple involved; the role of prenatal diagnosis in ascertaining transmission of virus to the fetus; the impact of preconceptional and periconceptional infections on the prevalence of congenital infection; and the prevalence of congenitally infected babies born to mothers who were immune prior to pregnancy compared to the number born to mothers undergoing primary infection during pregnancy.
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PMID:Diagnosis and management of human cytomegalovirus infection in the mother, fetus, and newborn infant. 1236 75

In the pre-vaccination era, rubella was regarded as only a mild exanthematous acute viral infection of children. The devastating effects of the disease were first identified in the early 1940s by an Australian ophthalmologist, and further confirmed during the 1962-65 rubella pandemic in Europe and the United States. They result from the transmission of the virus by infected pregnant women to their fetus. The resulting congenital rubella syndrome (CRS) comprises a lengthy list of abnormalities. The most common ones are deafness, ocular and cardiac defects and mental retardation. The objective of rubella vaccination, to which France has subscribed, is the elimination of CRS.
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PMID:Rubella control in France. 1519 60


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