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Behavioural Neurology
Volume 21 (2009), Issue 1-2, Pages 51-61
http://dx.doi.org/10.3233/BEN-2009-0235

Changes in Parahippocampal White Matter Integrity in Amnestic Mild Cognitive Impairment: A Diffusion Tensor Imaging Study

E. J. Rogalski,1 C. M. Murphy,2 L. deToledo-Morrell,2 R. C. Shah,3,4 M. E. Moseley,5 R. Bammer,5 and G. T. Stebbins2

1Cognitive Neurology and Alzheimer’s Disease Center at Northwestern University, Feinberg School of Medicine, Chicago, IL, USA
2Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
3Department of Family Medicine, Rush University Medical Center, Chicago, IL, USA
4Department of Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL, USA
5Department of Radiology Stanford University, Palo Alto, CA, USA

Received 16 October 2009; Accepted 16 October 2009

Copyright © 2009 Hindawi Publishing Corporation and the authors. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In the present study, changes in the parahippocampal white matter (PWM), in the region that includes the perforant path, were investigated, in vivo, in 14 individuals with amnestic mild cognitive impairment (aMCI) compared to 14 elderly controls with no cognitive impairment (NCI). For this purpose, (1) volumetry; (2) diffusion tensor imaging (DTI) derived measures of mean diffusivity (MD) and fractional anisotropy (FA); and (3) tractography were used. In addition, regression models were utilized to examine the association of PWM measurements with memory decline. The results from this study confirm previous findings in our laboratory and others, showing that compared to controls, individuals with aMCI have PWM volume loss. In addition to volume reduction, participants with aMCI demonstrated a significant increase in MD, but no difference in FA, both in the PWM region and in fibers modeled to pass through the PWM region. Further, the DTI metric of MD was associated with declarative memory performance, suggesting it may be a sensitive marker for memory dysfunction. These results indicate that there is general tissue loss and degradation (decreased volume; increased MD) in individuals with aMCI compared to older people with normal cognitive function. However, the microstructural organization of remaining fibers, as determined by measures of anisotropic diffusion, is not significantly different from that of controls.