Anterior corpus callosum atrophy and verbal fluency in multiple sclerosis.

To determine whether different portions of the corpus callosum (CC) are responsible for transferring the information of specific cognitive modalities, eighteen females with relapsing-remitting Multiple Sclerosis (MS) were studied using neuropsychological procedures and Magnetic Resonance Imaging (MRI). Measures of both anterior and posterior CC areas were obtained in patients with MS as well as in eighteen age and sex matched healthy controls. MRI scans were additionally analyzed for each patient in order to evaluate the extent of demyelinating lesions in both periventricular and subcortical areas. Patients with MS exhibited a significant decrease in both the anterior and posterior CC areas compared with normal subjects. The results of statistical analysis showed that, even when the effect of demyelinating lesions was taken into account within a regression equation, the atrophy of anterior CC area strongly affected the performance on verbal fluency task. These data emphasize the importance of the anterior CC area for the interhemispheric transfer of cognitive information associated with verbal fluency.