Investigators on behalf of the MS Study Group of the Italian Neurological Society performed a third cognitive assessment on 48 of 63 patients with childhood or juvenile MS in the original cohort and compared with 46 healthy controls. At year 5, 38% of the subjects with MS had cognitive impairment (defined as the failure of =/> 3 tests). Between years 2 and 5, 66.7% of patients showed improvement on the individual cognitive impairment index. However, comparing baseline and 5-year testing, cognitive impairment index deterioration occurred in 56% of the patients, improvement in 25%, and stability in 18.8%. Deteriorating performance was related to male sex, younger age and age at MS onset, and lower education. On multivariate analysis, none of these variables was demonstrated. Systematic neuropsychological screening is recommended in this population of pediatric–onset MS patients showing a heterogeneous cognitive outcome. 
COMMENTARY. Pediatric-onset MS (POMS) represents 3% to 5% of the whole MS population, and one third of the POMS population has cognitive impairment. MS-related cognitive problems are attributed to their occurrence during periods of brain growth, myelination, and neural-network maturation . MRI studies show reduced brain volume, and reduced thalamic volume and reduced corpus callosal area can distinguish children with cognitive impairment from those with intact cognitive performance [3, 4].