Cerebral white matter integrity and cognitive aging: contributions from diffusion tensor imaging.

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2009-12

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Abstract

The integrity of cerebral white matter is critical for efficient cognitive functioning, but little is known regarding the role of white matter integrity in age-related differences in cognition. Diffusion tensor imaging (DTI) measures the directional displacement of molecular water and as a result can characterize the properties of white matter that combine to restrict diffusivity in a spatially coherent manner. This review considers DTI studies of aging and their implications for understanding adult age differences in cognitive performance. Decline in white matter integrity contributes to a disconnection among distributed neural systems, with a consistent effect on perceptual speed and executive functioning. The relation between white matter integrity and cognition varies across brain regions, with some evidence suggesting that age-related effects exhibit an anterior-posterior gradient. With continued improvements in spatial resolution and integration with functional brain imaging, DTI holds considerable promise, both for theories of cognitive aging and for translational application.

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Brain, Neural Pathways, Nerve Fibers, Myelinated, Animals, Humans, Cognition, Cognition Disorders, Aging, Diffusion Tensor Imaging

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Published Version (Please cite this version)

10.1007/s11065-009-9113-2

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Madden, David J, Ilana J Bennett and Allen W Song (2009). Cerebral white matter integrity and cognitive aging: contributions from diffusion tensor imaging. Neuropsychology review, 19(4). pp. 415–435. 10.1007/s11065-009-9113-2 Retrieved from https://hdl.handle.net/10161/32174.

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Scholars@Duke

Madden

David Joseph Madden

Professor in Psychiatry and Behavioral Sciences

My research focuses primarily on the cognitive neuroscience of aging: the investigation of age-related changes in perception, attention, and memory, using both behavioral measures and neuroimaging techniques, including positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI).

The behavioral measures have focused on reaction time, with the goal of distinguishing age-related changes in specific cognitive abilities from more general effects arising from a slowing in elementary perceptual processes. The cognitive abilities of interest include selective attention as measured in visual search tasks, semantic and episodic memory retrieval, and executive control processes.

The behavioral measures are necessary to define the cognitive abilities of interest, and the neuroimaging techniques help define the functional neuroanatomy of those abilities. The PET and fMRI measures provide information regarding neural activity during cognitive performance. DTI is a recently developed technique that images the structural integrity of white matter. The white matter tracts of the brain provide critical pathways linking the gray matter regions, and thus this work will complement the studies using PET and fMRI that focus on gray matter activation.

A current focus of the research program is the functional connectivity among regions, not only during cognitive task performance but also during rest. These latter measures, referred to as intrinsic functional connectivity, are beginning to show promise as an index of overall brain functional efficiency, which can be assessed without the implementation of a specific cognitive task. From DTI, information can be obtained regarding how anatomical connectivity constrains intrinsic functional connectivity. It will be important to determine the relative influence of white matter pathway integrity, intrinsic functional connectivity, and task-related functional connectivity, as mediators of age-related differences in behavioral measures of cognitive performance.

Ultimately, the research program can help link age-related changes in cognitive performance to changes in the structure and function of specific neural systems. The results also have implications for clinical translation, in terms of the identification of neural biomarkers for the diagnosis of neural pathology and targeting rehabilitation procedures.

Song

Allen W Song

Professor in Radiology

The research in our lab is concerned with advancing structural and functional MRI methodologies (e.g. fast and high-resolution imaging techniques) for human brain imaging. We also aim to improve our understanding of functional brain signals, including spatiotemporal characterizations of the blood oxygenation level dependent contrast and alternative contrast mechanisms that are more directly linked to the neuronal activities. Additional effort is invested in applying and validating the developed methods to study human functional neuroanatomy.


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