Gross anatomy of the corpus callosum in Alzheimer's disease: regions of degeneration and their neuropsychological correlates

Background/Aims: Differences in the gross shape of the corpus callosum (CC) and its subregional areas were investigated on brain MRI of patients with probable Alzheimer's disease (AD) and age- and gender-matched healthy normal control subjects. The AD patients differed from the normal control subjects in terms of a more convex shape and a reduced area of the CC. Methods: As for the comparisons of the subregional areas of the CC, we adapted a splitting method which takes into account the modification of the global shape of the CC, and we implemented it by normalizing the CC, to avoid the bias introduced by the observed callosal shape variability. Results: The application of this method unveiled that the regional CC reductions were located in the anterior and posterior third of the CC, i.e. where small myelinated fibers are more frequent. None of the neuropsychological scores collected at the time of the MRI investigation of AD could predict a regional and/or overall callosal area reduction. The only measure that correlated with area of the isthmus of the CC was the MMSE that was administered to all participants. Conclusions: This latter result may be used as an in vivo indicator of the progress of neocortical disintegration in AD.