Journal of neural transmission
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Neuropathological studies in Alzheimer's disease (AD) indicate specific loss of layer III and V large pyramidal neurons in association cortex. These neurons give rise to long cortico-cortical connections, projecting through the corpus callosum, in an anterior-posterior topology. Based on these findings we hypothesized that regional corpus callosum atrophy may be a potential in vivo marker for neocortical neuronal loss in AD. ⋯ Our results indicate that regional corpus callosum atrophy in AD patients represents the loss of callosal efferent neurons in corresponding regions of the neocortex. As these neurons are a subset of cortico-cortical projecting neurons, region-specific corpus callosum atrophy may serve as a marker of progressive neocortical disconnection in AD. In combination with measurement of hippocampal atrophy, assessment of corpus callosum atrophy over time in individual patients is useful to evaluate effects on brain structure of currently developed drugs, thought to slow or modify AD progression.