Fiber connections between the cerebral cortex and the corpus callosum in Alzheimer's disease:: A diffusion tensor imaging and voxel-based morphometry study

Regional cortical atrophy in Alzheimer's disease (AD) most likely reflects the loss of cortical neurons. Several diffusion tensor imaging studies reported reduced fractional anisotropy (FA) in the corpus callosum in AD. The aim of this study was to investigate the association between reduced FA in the corpus callosurn and gray matter atrophy in AD. Thirteen patients with AD with a mean (+/- standard deviation) age of 68.3 years (+/- 11.5) and mean Mini Mental State Examination (MMSE) score of 21.8 (+/- 4.8) were recruited. There were 13 control subjects with a mean age of 66.7 years (+/- 6.4) and MMSE of 29.1 (+/- 0.7). We used voxel-based morphometry of gray matter maps and region of interest-based analysis of FA in the corpus callosurn. FA values of the anterior corpus callosurn in AD patients were significantly correlated with gray matter volume in the prefrontal cortex and left parietal lobes. FA values of the posterior corpus callosurn were significantly correlated with gray matter volume in the bilateral frontal, temporal, right parietal, and occipital lobes. In control subjects, no correlations were detected. Our findings suggest that decline of FA in the corpus callosurn may be related to neuronal degeneration in corresponding cortical areas.