Issue title: Alzheimer's Disease and Mild Cognitive Impairment: New Insights from Imaging
Article type: Research Article
Authors: Rogalski, E.J. | Murphy, C.M. | deToledo-Morrell, L. | Shah, R.C.; | Moseley, M.E. | Bammer, R. | Stebbins, G.T.
Affiliations: Cognitive Neurology and Alzheimer's Disease Center at
Northwestern University, Feinberg School of Medicine, Chicago, IL, USA | Department of Neurological Sciences, Rush University
Medical Center, Chicago, IL, USA | Department of Family Medicine, Rush University Medical
Center, Chicago, IL, USA | Department of Rush Alzheimer's Disease Center, Rush
University Medical Center, Chicago, IL, USA | Department of Radiology Stanford University, Palo
Alto, CA, USA
Note: [] Corresponding authors: Leyla deToledo-Morrell, Department of
Neurological Sciences, Rush University, 1653 W. Congress Parkway, Chicago, IL
60612, USA. Tel.: +1 312 942 5399; Fax: +1 312 563 3570; E-mail:
[email protected]; or Glenn Stebbins, Rush University Medical Center, 1725 W
Harrison, Suite 309, Chicago, IL 60612, USA. E-mail: [email protected]
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.
Keywords: MRI, dementia, perforant path, tractography, entorhinal cortex, magnetic resonance imaging, hippocampus, memory, mesial temporal lobe, volumetry
DOI: 10.3233/BEN-2009-0235
Journal: Behavioural Neurology, vol. 21, no. 1-2, pp. 51-61, 2009
Received 16 October 2009
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Accepted 16 October 2009
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Published: 2009
