The brain subcortical white matter and aging: A quantitative fractional anisotropy analysis

Substância branca cerebral e envelhecimento: análise com anisotropia fracionada quantitativa

Eliasz Engelhardt Denise Madeira Moreira Jerson Laks About the authors

Abstract

To study the integrity of hemispheric subcortical white matter by comparing normal young and elderly subjects using quantitative fractional anisotropy (DTI-FA).

Methods:

Subjects of two different age groups (young=12, elderly=12) were included. MR - GE Signa Horizon - 1.5T scans were performed. Cases with Fazekas scores £3 were assessed on FLAIR sequence. Standard parameters for DTI-FA were used. ROIs were placed at various sites of the subcortical white matter, and the genu and splenium of the midline corpus callosum. Analysis was performed using Functool. Statistics for anterior and posterior white matter, as well as the genu and splenium were compared between the groups. The study was approved by the Ethics Committee of IPUB-UFRJ and informed consent obtained.

Results:

DTI-FA showed lower anisotropy values in the anterior region (subcortical white matter and genu), but not in the posterior region (subcortical white matter and splenium), in elderly normal subjects compared to young subjects.

Conclusion:

The results may represent loss of integrity of anterior (frontal) white matter fibers in the elderly subjects. These fibers constitute important intra- and inter-hemispheric tracts, components of neural networks that provide cognitive, behavioral, motor and sensory integration. The loss of integrity of the anterior segments of the studied fiber systems with ageing, represents a disconnection process that may underlie clinical manifestations found in elderly subjects such as executive dysfunction.

Key words:
white matter; corpus callosum; fractional anisotropy; aging.

Resumo

Estudar a integridade da substância branca hemisférica subcortical, comparando sujeitos normais jovens e idosos, com anisotropia fracionada quantitativa (DTI-FA).

Métodos:

Foram incluídos sujeitos de dois grupos etários (jovem=12, idoso=12). Obtidas imagens de MR - GE Signa Horizon - 1.5T. Escore de Fazekas £3 avaliado na sequência em FLAIR. Utilizados parâmetros padrão para DTI-FA. ROIs colocados em locais variados da substância branca subcortical, e no joelho e esplênio do corpo caloso na linha média. Análise com Functool. Estatística para comparar a substância branca anterior e posterior entre os grupos. Aprovado pela Comissão de Ética do IPUB-UFRJ, consentimento informado obtido.

Resultados:

DTI-FA mostrou redução dos valores de anisotropia na região anterior (substância branca subcortical e joelho), porém não na região posterior (substância branca subcortical e esplênio), nos sujeitos normais idosos em comparação aos jovens.

Conclusão:

Os resultados podem ser considerados como representando perda da integridade das fibras da substância branca anterior (frontal) no sujeitos do grupo idoso. Tais fibras constituem os importantes feixes intra- e inter-hemisféricos, componentes de redes neurais relacionadas com integração cognitiva, comportamental, motora e sensorial. A perda da integridade com o envelhecimento dos segmentos anteriores dos sistemas de fibras estudados representa um processo de desconexão que pode estar subjacente a manifestações clínicas, como a disfunção executiva, eventualmente encontradas em sujeitos idosos.

Palavras-chave:
substância branca; corpo caloso; anisotropia fracionada; envelhecimento.

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Publication Dates

  • Publication in this collection
    Jul-Sep 2009

History

  • Received
    21 May 2009
  • Accepted
    06 Aug 2009
Academia Brasileira de Neurologia, Departamento de Neurologia Cognitiva e Envelhecimento R. Vergueiro, 1353 sl.1404 - Ed. Top Towers Offices, Torre Norte, São Paulo, SP, Brazil, CEP 04101-000, Tel.: +55 11 5084-9463 | +55 11 5083-3876 - São Paulo - SP - Brazil
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