Paediatric-onset multiple sclerosis, an inflammatory demyelinating disease of the CNS, comprises 2–10% of all multiple sclerosis cases. It is characterised by a high MRI lesion burden, 1 Yeh EA Weinstock-Guttman B Ramanathan M et al. Magnetic resonance imaging characteristics of children and adults with paediatric-onset multiple sclerosis.

Brain. 2009; 132: 3392-3400

high relapse frequency, and an altered trajectory of age-related brain growth. 2 Gorman MP Healy BC Polgar-Turcsanyi M Chitnis T Increased relapse rate in pediatric-onset compared with adult-onset multiple sclerosis.

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, 3 Aubert-Broche B Fonov V Narayanan S et al. Onset of multiple sclerosis before adulthood leads to failure of age-expected brain growth.

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Fatigue and depressive symptoms are reported by up to 75% of children with multiple sclerosis and up to 50% can have cognitive deficits, with progressive worsening through time. 4 Amato MP Goretti B Ghezzi A et al. Neuropsychological features in childhood and juvenile multiple sclerosis: five-year follow-up.

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Growing evidence suggests that factors such as diet, physical activity, and body habitus can mediate disease outcomes, 5 Petrin J Fiander M Doss P et al. A scoping review of modifiable risk factors in pediatric onset multiple sclerosis: building for the future.

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and the relationship between these factors might be explained by the microbiome.