Determination of trace elements in brain of elderly people in different cognitive status / Determinação de elementos traço no encéfalo de idosos em diferentes estados cognitivos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Among the many hypotheses concerning the etiology of Alzheimers disease (AD), studies regarding the involvement of trace elements have gained considerable attention. This study aimed to compare Br, Fe, K, Na, Rb, Se and Zn concentrations in brain of elderly people in different cognitive status and between brain regions in postmortem brains belonging to the Brazilian Aging Brain Study Groups Brain Bank. Protocols were approved by the responsible ethics committee. The cases were divided into three groups, according to clinical and neuropathological evaluations: (1) AD group: individuals with clinical symptoms and neuropathological hallmarks of AD (n=13), (2) NN group: individuals without clinical symptoms and neuropathological hallmarks of AD (n=11) and (3) RC group: individuals cognitively normal but with neuropathological hallmarks of AD (n=4). Neuropathological examinations were carried out based on accepted criteria, using immunohistochemistry. Diagnosis of dementia was established through a postmortem interview with an informant. Element concentration in the hippocampus and medium frontal cortex was determined using instrumental neutron activation analysis. Certified reference materials were analyzed to assure the quality of the analytical results. Statistical analysis of the results obtained in the brain tissue was performed using the Minitab v15 and SPSS v11 package. Variables were compared among groups using repeated measurement analyses of the variances. Reference material analysis results demonstrated that neutron activation analysis is a precise and exact method for element concentration analysis of the human brain. The results of the brain analysis demonstrated a decrease of Rb concentration in the brains of AD individuals compared to the NN and RC individuals. Furthermore, there is a decrease of K concentration and an increase of Na concentration in the brains of AD individuals compared to the NN individuals. An increase of Fe and Se was also verified in the AD group when compared to the NN group. Comparison of the hippocampus and frontal area concentration demonstrated a difference in the concentration of these two areas for many elements. The elevated concentration of Rb in the RC group when compared to the DA groups and the reduction in the DA groups when compared to the NN group suggest that Rb has a role in the protection mechanism against AD. However, changes in the Rb concentrations, as well as changes in the Na e K concentrations could be secondary to the pathological process. The elevated concentration of Fe could be a toxic factor in AD and the elevated concentration of Se could be a protection mechanism. Whether element deposition in AD is a primary or secondary event remains to be determined. As a result of the differences found in the concentrations of elements highlight the importance of having ideal sampling to determine element composition of brain tissue

ASSUNTO(S)

encéfalo doença de alzheimer elementos cognição alzheimers disease elderly elements aging brain envelhecimento idoso cognition

ACESSO AO ARTIGO

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