The corpus callosum in Pick's disease, Alzheimer's disease, and amyotrophic lateral sclerosis: gliosis implies possible clinical consequence.

Abstract

Lesions of the corpus callosum have the potential to interfere with a neurologically impaired individual's ability to function in day-to-day activities, since the corpus callosum is important for a number of higher-order activities that involve information transfer between the left and right hemispheres. Even in normal individuals, callosal lesions may lead to apraxia, agraphia, and even an alien hand syndrome whereby the person is unable to control the actions of a hand. It is easy to envisage that callosal damage could compound cognitive symptoms in individuals with dementia. However, despite the common presence of apraxia in dementia, physicians and other healthcare providers rarely focus on callosalfunction in dementia patients. The current manuscript compares pathological data from a variety of patients with dementia with age-matched control subjects showing callosal gliosis in neurodegenerative diseases including Alzheimer's disease (AD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis. We conclude that callosal gliosis is not uncommon, particularly in patients with AD and FTD. Given the severity of this pathology in some cases, we cannot exclude the possibility that it is clinically relevant. Clinical implications are discussed, and it is recommended that further studies be done to determine whether there is a relevant clinical correlate.