Article

Diffusion Tensor Imaging detects age-related white matter change over a two-year follow-up which is associated with working memory decline

Clinical Neuroscience, St George's University of London, London, UK.
Journal of neurology, neurosurgery, and psychiatry (Impact Factor: 5.58). 09/2009; 81(1):13-9. DOI: 10.1136/jnnp.2008.167288
Source: PubMed

ABSTRACT Diffusion tensor imaging (DTI) is a sensitive method for detecting white matter damage, and in cross sectional studies DTI measures correlate with age related cognitive decline. However, there are few data on whether DTI can detect age related changes over short time periods and whether such change correlates with cognitive function.
In a community sample of 84 middle-aged and elderly adults, MRI and cognitive testing were performed at baseline and after 2 years. Changes in DTI white matter histograms, white matter hyperintensity (WMH) volume and brain volume were determined. Change over time in performance on tests of executive function, working memory and information processing speed were also assessed.
Significant change in all MRI measures was detected. For cognition, change was detected for working memory and this correlated with change in DTI only. In a stepwise regression, with change in working memory as the dependent variable, a DTI histogram measure explained 10.8% of the variance in working memory. Change in WMH or brain volume did not contribute to the model.
DTI is sensitive to age related change in white matter ultrastructure and appears useful for monitoring age related white matter change even over short time periods.

Download full-text

Full-text

Available from: Rebecca A Charlton, Jul 02, 2015
0 Followers
 · 
122 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The structural integrity of the cerebral white matter, including that of the white matter lesions (WML) and of the surrounding normal appearing white matter (NAWM), can be assessed with diffusion tensor imaging (DTI), which is suggested to be of added value in the explanation of cognitive dysfunction in cerebral small vessel disease (SVD). We investigated the value of DTI of NAWM and WML in addition to conventional magnetic resonance imaging (MRI) parameters in the variance of cognitive performance in subjects with SVD. 499 individuals with SVD, 50-85 years, without dementia, underwent MRI scanning, including a DTI sequence. Grey matter, white matter (WM), and WML volume, number of microbleeds, lacunar and territorial infracts, and mean diffusivity (MD) and fractional anisotropy (FA) in NAWM, WML, and total WM were related to cognitive performance in multivariate regression analyses, after adjustment for age, gender, and education. All MRI parameters together accounted for 1-6% of the variance in cognitive function on top of 22-36% already explained by age, gender, and level of education. Both mean MD and FA of the NAWM, WML, and total WM did not substantially contribute to the explained variance of cognitive function, to that already explained by conventional MRI parameters. When considered separately, the MD of the (NA)WM had the strongest association with cognitive performance. In conclusion, DTI of NAWM and WML has limited additional value to conventional MRI parameters in the etiological explanation of the variance in cognitive function among individuals with SVD.
    Journal of Alzheimer's disease: JAD 07/2012; 32(3). DOI:10.3233/JAD-2012-120784
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dementia is one of the most disabling conditions. Alzheimer's disease and vascular dementia (VaD) are the most frequent causes. Subcortical VaD is consequent to deep-brain small vessel disease (SVD) and is the most frequent form of VaD. Its pathological hallmarks are ischemic white matter changes and lacunar infarcts. Degenerative and vascular changes often coexist, but mechanisms of interaction are incompletely understood. The term mild cognitive impairment defines a transitional state between normal ageing and dementia. Pre-dementia stages of VaD are also acknowledged (vascular mild cognitive impairment, VMCI). Progression relates mostly to the subcortical VaD type, but determinants of such transition are unknown. Variability of phenotypic expression is not fully explained by severity grade of lesions, as depicted by conventional MRI that is not sensitive to microstructural and metabolic alterations. Advanced neuroimaging techniques seem able to achieve this. Beside hypoperfusion, blood-brain-barrier dysfunction has been also demonstrated in subcortical VaD. The aim of the Vascular Mild Cognitive Impairment Tuscany Study is to expand knowledge about determinants of transition from mild cognitive impairment to dementia in patients with cerebral SVD. This paper summarizes the main aims and methodological aspects of this multicenter, ongoing, observational study enrolling patients affected by VMCI with SVD.
    04/2012; 2012(2090-8024):608013. DOI:10.1155/2012/608013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Determining the time of peak of cerebral maturation is vital for our understanding of when cerebral maturation ceases and the cerebral degeneration in healthy aging begins. We carefully mapped changes in fractional anisotropy (FA) of water diffusion for eleven major cerebral white matter tracts in a large group (831) of healthy human subjects aged 11-90. FA is a neuroimaging index of micro-structural white matter integrity, sensitive to age-related changes in cerebral myelin levels, measured using diffusion tensor imaging. The average FA values of cerebral white matter (WM) reached peak at the age 32 ± 6 years. FA measurements for all but one major cortical white matter tract (cortico-spinal) reached peaks between 23 and 39 years of age. The maturation rates, prior to age-of-peak were significantly correlated (r=0.74; p=0.01) with the rates of decline, past age-of-peak. Regional analysis of corpus callosum (CC) showed that thinly-myelinated, densely packed fibers in the genu, that connect pre-frontal areas, maturated later and showed higher decline in aging than the more thickly myelinated motor and sensory areas in the body and splenium of CC. Our findings can be summarized as: associative, cerebral WM tracts that reach their peak FA values later in life also show progressively higher age-related decline than earlier maturing motor and sensory tracts. These findings carry multiple and diverse implications for both theoretical studies of the neurobiology of maturation and aging and for the clinical studies of neuropsychiatric disorders.
    Neurobiology of aging 01/2012; 33(1):9-20. DOI:10.1016/j.neurobiolaging.2010.01.014