Selective changes in white matter integrity in MCI and older adults with cognitive complaints

Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, USA.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 08/2011; 1822(3):423-30. DOI: 10.1016/j.bbadis.2011.08.002
Source: PubMed


White matter changes measured using diffusion tensor imaging have been reported in Alzheimer's disease and amnestic mild cognitive impairment, but changes in earlier pre-mild cognitive impairment stages have not been fully investigated.
In a cross-sectional analysis, older adults with mild cognitive impairment (n=28), older adults with cognitive complaints but without psychometric impairment (n=29) and healthy controls (n=35) were compared. Measures included whole-brain diffusion tensor imaging, T1-weighted structural magnetic resonance imaging, and neuropsychological assessment. Diffusion images were analyzed using Tract-Based Spatial Statistics. Voxel-wise fractional anisotropy and mean, axial, and radial diffusivities were assessed and compared between groups. Significant tract clusters were extracted in order to perform further region of interest comparisons. Brain volume was estimated using FreeSurfer based on T1 structural images.
The mild cognitive impairment group showed lower fractional anisotropy and higher radial diffusivity than controls in bilateral parahippocampal white matter. When comparing extracted diffusivity measurements from bilateral parahippocampal white matter clusters, the cognitive complaint group had values that were intermediate to the mild cognitive impairment and healthy control groups. Group difference in diffusion tensor imaging measures remained significant after controlling for hippocampal atrophy. Across the entire sample, diffusion tensor imaging indices in parahippocampal white matter were correlated with memory function.
These findings are consistent with previous results showing changes in parahippocampal white matter in Alzheimer's disease and mild cognitive impairment compared to controls. The intermediate pattern found in the cognitive complaint group suggests the potential of diffusion tensor imaging to contribute to earlier detection of neurodegenerative changes during prodromal stages. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.

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    • "Subjective cognitive complaint can be assessed by one [20] or multiple questions [60] Complaint relates to episodic memory that query for changes compared to one's own past abilities [61], to one's peers [35], or based upon a functional ability [62]. Different complaint questions may relate differently to objective cognitive performance [63] without comparable clinical significance. "
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    ABSTRACT: Background: A cognitive concern from the patient, informant, or clinician is required for the diagnosis of mild cognitive impairment (MCI); however, the cognitive and neuroanatomical correlates of complaint are poorly understood. Objective: We assessed how self-complaint relates to cognitive and neuroimaging measures in older adults with MCI. Method: MCI participants were drawn from the Alzheimer's Disease Neuroimaging Initiative and dichotomized into two groups based on the presence of self-reported memory complaint (no complaint n = 191, 77 ± 7 years; complaint n = 206, 73 ± 8 years). Cognitive outcomes included episodic memory, executive functioning, information processing speed, and language. Imaging outcomes included regional lobar volumes (frontal, parietal, temporal, cingulate) and specific medial temporal lobe structures (hippocampal volume, entorhinal cortex thickness, parahippocampal gyrus thickness). Results: Linear regressions, adjusting for age, gender, race, education, Mini-Mental State Examination score, mood, and apolipoprotein E4 status, found that cognitive complaint related to immediate (β = -1.07, p < 0.001) and delayed episodic memory performances assessed on a serial list learning task (β = -1.06, p = 0.001) but no other cognitive measures or neuroimaging markers. Conclusions: Self-reported memory concern was unrelated to structural neuroimaging markers of atrophy and measures of information processing speed, executive functioning, or language. In contrast, memory self-complaint related to objective verbal episodic learning performance. Future research is warranted to better understand the relation between cognitive complaint and surrogate markers of abnormal brain aging, including Alzheimer's disease, across the cognitive aging spectrum.
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    • "E-mail address: memory decline [6], increased risk of AD [7] [8] [9], and have been associated with the presence of neurobiological markers of AD (e.g., grey matter atrophy [10] [11] [12] [13] [14], white matter integrity [15], amyloid burden [16] [17], and AD pathology at autopsy [18]). Although APOE ε4 has been associated with a greater prevalence of SCC [19] [20] [21], very limited research has addressed whether SCC predict memory decline in APOE ε4 carriers [22]. "
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