# Early-life and adult body mass index in relation to MS disability progression

## TL;DR

Higher body mass index in early adulthood and at MS diagnosis is linked to faster disability progression in multiple sclerosis patients.

## Contribution

This study reveals how early-life and adult BMI jointly influence long-term MS disability outcomes.

## Key findings

- High BMI at age 20 is associated with higher disability at MS diagnosis.
- Persistent high BMI increases the risk of disability progression compared to normal BMI at both age 20 and diagnosis.
- Early-life excess weight alone does not predict MS progression, but combined with adult obesity, it amplifies risks.

## Abstract

The influence of body weight across the life course on multiple sclerosis (MS) progression remains incompletely understood. While excess body mass at diagnosis is associated with disability progression, it is unclear how early-life and adult BMI jointly affect long-term outcomes. We aimed to investigate the separate and combined effects of BMI at age 20 and at diagnosis on MS progression.

We studied 2940 individuals with relapsing-onset MS from a population-based case–control study with prospective follow-up through the Swedish MS registry. BMI was calculated from self-reported weight at age 20 and at diagnosis. Outcomes included confirmed disability worsening (CDW), and time to reach EDSS 3 and EDSS 4. Cox regression and general linear models were used to examine associations between BMI and MS progression, including interaction terms.

High BMI (> 28 kg/m2) at age 20 was associated with higher disability at diagnosis (β = 0.15, p = 0.0015), while BMI at diagnosis predicted increased risk of progression. Compared to individuals with BMI ≤ 28 kg/m2 at both time points, those with persistent elevated BMI had higher risks of CDW (HR 1.28, 95% CI 1.01–1.63), EDSS 3 (HR 1.64, 95% CI 1.21–2.24), and EDSS 4 (HR 1.51, 95% CI 1.00–2.39). Risks were increased, though less pronounced, among those with high BMI only at diagnosis. Early-life excess weight alone was not associated with progression. Interaction models suggested a stronger effect of adult BMI in the presence of early excess weight.

High BMI at diagnosis was associated with faster disability progression, particularly when present since early adulthood. These findings underscore the potential benefits of early weight management in MS.