Academic literature on the topic 'Neuropsychological toxicology'

Humans exposed to neurotoxins may exhibit alterations in cognitive and affective functioning and report a wide range of subjective symptoms. The multidisciplinary field of “neuropsychological toxicology” provides a framework for the systematic assessment and interpretation of adverse effects. Neuropsychological assessment is of interest not only to clinicians, but also to regulatory and legislative authorities. The importance of neuropsychological toxicology in the area of occupational risk research is increasingly being recognized. Possible fields of application include behavioral monitoring for preventive purposes, expert assessment in the context of compensation cases, and treatment in rehabilitation programs. This article reviews common research approaches, selected findings, and methodological problems of this emerging discipline and summarizes the implications for related fields of psychological research.

Five chemicals indigenous to the dental office environment that may cause toxic effects are formaldehyde, phenol, acrylic, mercury, and nitrous oxide. These chemicals create abnormal stress on physiological and psychological systems of the body resulting in symptomatology and pathology when the body defenses can no longer maintain homeostasis by adaptation. This study demonstrated serious behavioral consequences of chemical and heavy metal exposure. This study provided evidence that a significant percentage of dental office personnel who are exposed to the dental office chemicals show psycho neurological dysfunction. It was concluded that these individuals suffer adverse reactions to the chemicals in their work environment. The problem areas included perceptual motor difficulty in cognitive functioning, concern with bodily functions, despondency, and interpersonal problems.

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O Manganês (Mn) é um elemento essencial ao corpo humano. O funcionando do Mn no organismo ocorre através de um mecanismo homeostático eficaz que mantem os níveis deste metal em concentrações ótimas. No entanto, altas concentrações de Mn no organismo podem acarretar prejuízos ao Sistema Nervoso Central, uma vez que, possui um potencial neurotóxico. O excesso de Mn no organismo tem sido associado a prejuízos neuropsicológicos em crianças e adultos. Os estudos com crianças expostas ao Mn retratam associações com a diminuição do desempenho em testes de Coeficiente Intelectual (QI), Desenvolvimento Psicomotor, Memória, Atenção e Função Motora. Objetivos: O presente trabalho tem por objetivo avaliar o desempenho neuropsicológico e comportamental de crianças em idade escolar e a associação com a exposição ao manganês. Materiais e Métodos: Participaram deste estudo 78 díades criança-mãe/responsável, crianças com idades entre 7 e 12 anos, e residentes em duas comunidades, Cotegipe e Santa Luzia, do município de Simões-Filho, situadas na região metropolitana de Salvador - Bahia, Brasil. Essas comunidades estão sob influência da poluição atmosférica gerada pelo processo de produção de ligas ferro-manganês de uma metalúrgica. Foi aplicada uma bateria neuropsicológica nas crianças compreendendo os domínios cognitivos: Inteligência, Memória, Atenção, Funções Executivas e Função Motora. Os pais ou responsáveis responderam a um questionário sociodemográfico e ao Child Behavior Checklist (CBCL), enquanto que os professores responderam à Escala Abreviada de Conners. Os níveis de Mn foram determinados por espectrometria de absorção atômica com forno de grafite e os resultados expressos em μg/g de Mn no cabelo (MnC). O desempenho neuropsicológico das crianças das duas comunidades foi comparado segundo testes estatísticos paramétricos e não paramétricos. Realizaram-se análises de correlação bivariada e análise de regressão múltipla para a investigação das associações entre o desempenho neuropsicológico e os níveis de Mn no cabelo. Resultados: Encontramos um desempenho inferior das crianças da comunidade de Santa Luzia, situada entre 2,5 a 3,5 km da fábrica, em relação à comunidade de Cotegipe situada até 2 km da Fábrica, nos seguintes testes: Fluência Fonológica (p=0,03), Cubos-WISC-III (p=0,04), Dígitos Ordem Indireta (OI) (p=0,002), Cubos de Corsi Ordem Direta (OD) (p=0,006), e maior quantidade de Erros em Nomeação (p=0,047). A análise do tamanho de efeito revelou que as diferenças entre as comunidades foi pequena, apenas a diferença entre o desempenho em Fluência Fonológica obteve uma magnitude de efeito moderada (d de 11 cohen= 0,56). Considerando os demais testes, o desempenho neuropsicológico das comunidades de Cotegipe e Santa Luzia foi semelhante. A análise do desempenho neuropsicológico geral das crianças das duas comunidades evidenciou escores abaixo da média que crianças com desenvolvimento típico em: Cubos (WISC-III), Tempo de Reação e Erros por Ação (TAVIS-III), Produzindo Palavras (Fluência Fonológica) e Soma dos Erros em Inibindo Respostas (NEPSY-II). A análise de rede das variáveis que estiveram correlacionadas significativamente (p<0,05) evidenciou uma rede coesa e com grau de nós interligados alto. As variáveis que apresentaram maior grau de correlações significativas com as demais foram: os escores em Dígitos OI, Cubos de Corsi OI, Fluência Fonológica, e o tempo total do Grooved Pegboard em ambas as mãos. O QI da criança correlacionou-se diretamente e moderadamente com o QI materno (r=0,47; p<0,001). Foram encontradas associações inversas entre log de MnC e os escores dos testes de QI, Dígitos OD e OI e recordação livre imediata em Memória para Lista (NEPSY-II). Observou-se a associação positiva entre log de MnC e velocidade motora, problemas de atenção, hiperatividade e comportamentos externalizantes. Conclusão: Os resultados confirmam que as crianças estão sob efeito da exposição crônica ao Mn advindo das emissões da planta metalúrgica. Concentrações elevadas de MnC foram associadas a um menor desempenho em medidas neuropsicológicas e comportamentais. Os resultados corroboram evidências crescentes que indicam aumento de comportamentos de impulsividade e externalizantes, assim como dificuldade de inibição de respostas, associados a exposição ao Mn e com possíveis efeitos sob o sistema dopaminérgico e de auto-regulação. Manganese (Mn) is an essential element to the human body. The functioning of Mn in the body occurs through a homeostatic mechanism that maintains effective levels of this metal in optimal concentrations. However, high concentrations of Mn in the body may cause damage to the central nervous system, assuming that Mn has a neurotoxic potential. Excess Mn in the body has been associated with neuropsychological impairments in children and adults. Studies with children exposed to Mn indicate associations with decreased performance on tests of intellectual coefficient (IQ), Psychomotor Development, Memory, Attention and Motor Function. Objectives: The aim of this study is to assess the behavioral and neuropsychological performance in school age children and the association with manganese exposure. Materials and Methods: The study included 78 dyads children-mother/caregiver, children aged between 7 and 12 years old, and residents in two communities, Cotegipe and Santa Luzia, in the district of Simões-Filho, located in the state of Bahia, Brazil. These communities are under the influence of pollution generated by the production process of a iron-manganese alloy plant. Was administered a neuropsychological battery for children including the cognitive domains: Intelligence, Memory, Attention, Executive Functions and Motor Function. Parents or caregivers answered a sociodemographic questionnaire and the Child Behavior Checklist (CBCL), while teachers answered to the Abbreviated Conners Scale. The levels of Mn were determined by atomic absorption spectrometry with graphite furnace and the results expressed in μg/g-Mn in the hair (MnH). The neuropsychological performances of children of both communities were compared according to parametric and non-parametric statistical tests. Bivariate correlations and multiple regression analysis were applied to investigate the associations between neuropsychological performance and manganese biomarkers’ levels. Results: We found a lower performance of children in the community of Santa Luzia, located between 2.5 to 3.5 km radius from the iron-manganese alloy plant, in relation to the community of Cotegipe located within 2 km radius of the plant, in the following tests: Phonologic Fluency (p = 0.03 ), Block Design -WISC-III (p = 0.04), Digit Span-Indirect Order (IO) (p = 0.002), Corsi Block - Direct Order (DO) (p = 0.006), and greater number of Naming Errors (p = 0.047). The effect size analysis revealed that the differences between communities was small, only the difference between the performance on Phonologic Fluency obtained a moderate effect size (Cohen d = 0.56). Considering the other tests, neuropsychological performance of both communities was similar. The analysis of general neuropsychological performance of 13 children of both communities showed below average scores than children with typical development in: Block Design (WISC-III), Reaction Time and Commission Errors (TAVIS-III), Word Generation (Phonologic Fluency) and Total Inhibition Errors (NEPSY-II). A network analysis of the variables that were significantly correlated (p <0.05) showed a cohesive network with a high degree of interconnected nodes. The variables that have higher degree of significant correlations with the others were: Digit Span IO, Corsi Block IO, Phonologic Fluency, and Grooved Pegboard total time on both hands. The child's IQ correlated directly and moderately with maternal IQ (r = 0.47, p <0.001). We found inverse associations between log MnH and scores on IQ, Digit Span DO and IO and immediate free recall in Memory List (NEPSY-II). We observed a positive association between log MnH and motor speed, attention problems, hyperactivity and externalizing behaviors. Conclusion: The results showed that the children of these communities are under the effect of chronic exposure to Mn emissions arising from the iron-manganese alloy plant. High levels of MnH were associated with lower performance on neuropsychological and behavioral measures. The results corroborate growing evidence that indicate increased impulsivity and externalizing behaviors, as well as difficulty to inhibition of responses, associated with Mn exposure and possible effects on the dopamine system and self-regulation.

Neuropsychological toxicology investigates the impact of chemical exposure on the structure and functioning of the nervous system and by implication the neuropsychological performance of affected individuals. As in mainstream neuropsychology, brain damage is assessed by measuring changes in the cognitive, psychomotor and emotional domains using diagnostic neuropsychological tests. The field of neuropsychological toxicology has undergone significant growth in the last 20 years, amongst growing concerns over people’s potential everyday exposure to approximately 70 000 chemicals. Growing awareness of the possible dangers associated with neurotoxic exposure has lead to the increased regulation of exposure levels especially in industrial settings. This in turn has lead to a gradual shift in neuropsychological toxicology from the assessment of severe neurotoxic damage to the evaluation of subclinical signs, which may develop into disabling damage over many years of exposure. The assessment of these subclinical signs has proven to be tricky as they cannot always be measured through diagnostic tests and may be mimicked or hidden by numerous confounding variables. The need for the effective assessment of these subclinical signs has created a need for more sensitive tests and improved research methodology. This paper uses evidence from cellular pathology and anatomical pathology (dynamic brain localisation theory) as a guide for the selection of neuropsychological tests. The purpose of the paper is to review the neuropsychological outcomes of toxic exposure, with an emphasis on test sensitivity (screening) and specificity (diagnostic) to carbon disulphide (solvent), manganese (metal) and organophosphate (pesticide) exposure. Findings from this review point to the possible advantages of the continued use of standardised neuropsychological batteries that enable the assessment of global functions in addition to tests that measure deficits associated with the toxicodynamics of the neurotoxin under investigation. Methodological recommendations include the use of simultaneous cross-sectional and longitudinal designs to control for numerous confounding variables and correlation designs to determine dose-response relationships. Future studies need to address the sensitivity and specificity criteria of various neuropsychological measures utilising the principle of neurotoxicodynamics.
Dissertation (MA (Research Psychology))--University of Pretoria, 2007.
Psychology
MA
unrestricted

BACKGROUND: Many women of reproductive age are employed in industries involving exposure to organic solvents. Animal toxicological studies and human case reports demonstrate that exposure to organic solvents can cause neuropsychological deficits in exposed offspring; however, there is limited data from prospective controlled human studies. OBJECTIVE: To compare neuropsychological functioning between children whose mothers were occupationally exposed to organic solvents during pregnancy with a non-exposed matched comparison group. METHODS: Participants were 48 women who had previously contacted the Motherisk Program in Toronto, Canada during pregnancy regarding occupational exposure to organic solvents and a matched comparison group of women with no known exposure to teratogens during pregnancy. Children (18 months to 8 years 11 months at time of study) were compared in areas of cognitive, language, motor, and behavioral functioning. RESULTS: Children whose mothers were exposed to organic solvents during pregnancy displayed a lower level of functioning when compared with their matched peers in areas of cognitive, language, motor, and behavioral domains. Although the scores on measures of behavioral functioning were not in the clinical range, the mothers of exposed children reported more challenging behavioral problems. In order to determine whether exposure predicted neuropsychological outcomes above and beyond maternal intellectual functioning, hierarchical regressions were run with maternal IQ and maternal education at Step 1and exposure status added at Step 2. In utero exposure to organic solvents predicted lower sores on global measures of Verbal IQ, receptive and expressive language scales above and beyond maternal intellectual functioning. Factors associated with higher levels of exposure (detecting odor, longer duration and total number of toxicity symptoms) was associated with poorer outcome on behavioral and motor functioning tests. CONCLUSION: Despite the fact that the exposed mothers experienced minimal symptoms of toxicity, detrimental effects were still evident in their offspring. Current safety standards for exposure were designed for adults and need to be reevaluated. Further studies addressing exposure to specific organic solvents, dose, and gestational timing of exposure are warranted.