MRI results showed that children with MS have overall smaller brain volumes than expected for their age. Regional analysis taking into account differences in head size showed that the thalamus, a key brain structure involved in attention, arousal, and memory, was reduced by 11.9 percent in the MS patients. The corpus callosum, which is the largest white matter tract in the brain and important for transmitting information between brain hemispheres, was reduced by five percent.
“A key component of MS onset during childhood relates to its effect on the developing brain,” says Till. “Overall, our findings suggest that the young age of childhood-onset MS patients does not protect them from the negative impact of the disease. We know that the earlier a patient develops MS, the greater likelihood their language development will be negatively impacted,” she says.
Approximately 24 to 40 percent of MS patients in the study showed impaired cognitive performance on measures of processing speed and visuomotor integration (e.g. copying designs). Impairments were also noted in complex attention (e.g. simultaneously attending to multiple stimuli), visual-spatial abilities, expressive language, and executive functions such as shifting attention back and forth between two stimuli, planning and organizing. In addition, the children identified with global cognitive impairment tended to be male and to have the disease for a longer duration.
“Interestingly, physical disability did not correlate with cognitive impairment, suggesting that cognitive dysfunction can be present in the absence of physical disability,” Till says.