Association Between Early-Life and Premorbid Measurements of Body Composition and Risk of Motor Neuron Disease: A Prospective Cohort Study in the UK Biobank.

Objective: The objective of this study was to investigate the association between developmental and premorbid body composition measurements and the risk of motor neuron disease (MND).

Methods: We performed a cohort study in the UK Biobank to assess the association of developmental body metrics and premorbid body composition measures (using 28 measurements and 7 patterns of body composition) with the risk of MND. Among participants with longitudinal measures, we compared the changes in body composition over time between individuals who later developed MND and those who remained free of MND.

Results: Among the 412,691 individuals included in this study, 549 people received an MND diagnosis during the follow-up visit. Higher birth weight was associated with an increased risk of MND among individuals born over 4 kg (hazard ratio [HR] per kg increase = 2.21, 95% confidence interval [CI] = 1.38-3.55), and taller adult height was associated with an increased risk of MND (HR per 5 cm increase = 1.10, 95% CI = 1.03-1.17). We observed that measures of elevated fat mass were associated with a lower risk of MND more than 5 years before diagnosis. A higher "leg-dominant fat distribution" pattern was associated with an increased risk whereas higher "muscle strength" was associated with a reduced risk of MND 5 years before diagnosis. Longitudinal analyses indicated a faster decline in measures of fat mass and muscle strength, as well as a shift in fat distribution from arm to leg dominant, among individuals who later developed MND, compared with others.

Interpretation: Body composition at early and middle age may be indicative of the risk of MND development. ANN NEUROL 2024.