TOPLINE:

Reduced outdoor activity in early childhood, particularly during the winter season, was associated with higher odds of paediatric multiple sclerosis (MS) across multiple early-life age groups.

METHODOLOGY:

• Researchers in Italy conducted a multicentre case-control study to evaluate whether reduced outdoor activity in early childhood, used as a proxy for sun exposure, was associated with an increased risk for paediatric MS.
• They included 114 patients with paediatric MS (mean age, 16.8 years; 77.2% girls; disease duration ≤ 5 years) and 121 control participants without inflammatory disorders of the central nervous system (mean age, 13.5 years; 54.4% girls) between 2020 and 2023.
• Data on environmental exposures were collected using a standardised questionnaire, which assessed outdoor activity (playing, sports, walking, and similar activities) by season (spring, summer, autumn, and winter) and age group (first year of life, 1-2 years, 3-5 years).
• Reduced outdoor activity was defined as less than 60 min/wk of outdoor engagement.

TAKEAWAY:

• During winter, reduced outdoor activity in the first year of life was reported by 73.7% of patients vs 46.3% of control participants and was associated with approximately threefold higher odds of paediatric MS (adjusted odds ratio, 3.02; P = .002).
• Similarly, low outdoor activity during winter was associated with 2.72-fold and 2.66-fold higher odds of paediatric MS at ages 1-2 and 3-5 years, respectively (P < .05 for both).
• During autumn, reduced outdoor activity in the first year of life and being aged 3-5 years was associated with nearly twofold and more than twofold increased odds of paediatric MS, respectively (P < .05 for both).
• During spring, reduced outdoor activity was only associated with more than twofold increased odds of paediatric MS in the first year of life (P = .039). No significant association was observed during summer.

IN PRACTICE:

"PedMS [paediatric MS] cases consistently reported lower outdoor activity across all seasons and age groups compared to controls, with the difference being most pronounced in winter. The strongest adjusted associations for increased PedMS risk were specifically linked to low outdoor time during the winter season across all early childhood age groups (ages 0-5)," the authors wrote.

SOURCE:

This study was led by Silvy Pilotto, University of Ferrara, Sant'Anna University Hospital, Ferrara, Italy. It was published online on May 24, 2026, in Neurology and Therapy.

LIMITATIONS:

The study's modest sample size and failure to achieve the planned case-control matching may have limited statistical power to detect subtle seasonal effects. The misclassification of outdoor activities due to parental reporting could not be ruled out. The observational case-control design may have introduced residual confounding.

DISCLOSURES:

This study received support from Fondazione Italiana Sclerosi Multipla. One author disclosed being an editorial board member of Neurology and Therapy.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.