Affiliations: [a] The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA | [b] Department of Psychiatry, New York University School of Medicine, New York, NY, USA
Correspondence:
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Correspondence to: Babak A. Ardekani, PhD, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA. Tel.: +1 845 398 5490; Fax: +1 845 398 5472; E-mail: ardekani@nki.rfmh.org.
Note: [1] Data used in preparation of this article were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database (http://adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp-content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf
Abstract: Background:Corpus callosum (CC) size and shape have been previously studied in Alzheimer’s disease (AD) with the majority of studies having been cross-sectional. Due to the large variance in normal CC morphology, cross-sectional studies are limited in statistical power. Determining individual rates of change requires longitudinal data. Physiological changes are particularly relevant in mild cognitive impairment (MCI), in which CC morphology has not been previously studied longitudinally. Objective:To study temporal rates of change in CC morphology in MCI patients over a one-year period, and to determine whether these rates differ between MCI subjects who converted to AD (MCI-C) and those who did not (MCI-NC) over an average (±SD) observation period of 5.4 (±1.6) years. Methods:We used a novel multi-atlas based algorithm to segment the mid-sagittal cross-sectional area of the CC in longitudinal MRI scans. Rates of change of CC circularity, total area, and five sub-areas were compared between 57 MCI-NC and 81 MCI-C subjects. Results:The CC became less circular (−0.89% per year in MCI-NC, −1.85% per year in MCI-C) with time, with faster decline in MCI-C (p = 0.0002). In females, atrophy rates were higher in MCI-C relative to MCI-NC in total CC area (p = 0.0006), genu/rostrum (p = 0.005), and splenium (0.002). In males, these rates did not differ between groups. Conclusion:A greater than normal decline in CC circularity was shown to be an indicator of prodromal AD in MCI subjects. This measure is potentially useful as an imaging biomarker of disease and a therapeutic target in clinical trials.
Keywords: Alzheimer's disease, brain, circularity, corpus callosum, magnetic resonance imaging, mild cognitive impairment, shape analysis
