Memory performance and normalized regional brain volumes in patients with pediatric-onset multiple sclerosis

Studies in adults with multiple sclerosis (MS) have associated regional brain abnormalities with memory impairment. While memory problems in children with MS are often reported, little is known about the neural correlates that may contribute to these difficulties. We measured verbal and nonverbal memory using the Test of Memory and Learning (TOMAL-2) in 32 children and adolescents with MS and 26 age- and sex-matched healthy controls. Memory performance was correlated with volumetric measures of the whole brain, hippocampus, amygdala, and thalamus. Brain volumes were normalized for age and sex using magnetic resonance imaging (MRI) data from the National Institutes of Health MRI Study of Normal Brain development. With the exception of story recall, performance on memory tests was similar to that of the control group. Relative to controls, patient with MS showed reduced volume in the whole brain (p < .001), amygdala (p < .005), and thalamus (p < .001), but not the hippocampus. In the patient group, word-list learning correlated with whole brain volume (r = .53) and hippocampal volume (r = .43), whereas visual recognition memory correlated with thalamic volume (r = .48). Findings are consistent with the well-established role of the hippocampus in learning and consolidation and also highlight the importance of diffuse brain pathology on memory function.