Dissociation between corpus callosum atrophy and white matter pathology in Alzheimer's disease

Objective: To determine whether the size of the corpus callosum is related to the extent of white matter pathology in patients with AD and age- matched healthy control subjects. Methods: White matter hyperintensity load and corpus callosum size were compared between 20 clinically diagnosed AD patients and 21 age-matched healthy control subjects. We investigated the effect of age and disease severity on corpus callosum size and white matter hyperintensity, in addition to the relation between corpus callosum areas and white matter hyperintensity load. Results: We found significant regional atrophy of the corpus callosum in AD when compared with control subjects, although the groups did not differ in their white matter hyperintensity load. We further showed a region-specific correlation between corpus callosum size and white matter hyperintensity in the control group but not in AD patients. In the AD group, corpus callosum size correlated with age and dementia severity, whereas white matter hyperintensity correlated only with age. Conclusion: Corpus callosum atrophy in AD can occur independent of white matter degeneration, likely reflecting specific AD pathology in projecting neurons.