Body size interacts with the structure of the central nervous system: A multi-center in vivo neuroimaging study
Authors: Labounek René , Bondy Monica T. , Paulson Amy L. , Bédard Sandrine , Abramovic Mihael , Alonso-Ortiz Eva , Atcheson Nicole T , Barlow Laura R. , Barry Robert L. , Barth Markus , Battiston Marco , Büchel Christian , Budde Matthew D. , Callot Virginie , Combes Anna , Leener Benjamin De , Descoteaux Maxime , Loureiro de Sousa Paulo , Dostál Marek , Doyon Julien , Dvorak Adam V. , Eippert Falk , Epperson Karla R. , Epperson Kevin S. , Freund Patrick , Finsterbusch Jürgen , Foias Alexandru , Fratini Michela , Fukunaga Issei , Gandini Wheeler-Kingshott Claudia A. M. , Germani GianCarlo , Gilbert Guillaume , Giove Federico , Grussu Francesco , Hagiwara Akifumi , Henry Pierre-Gilles , Horák Tomáš , Hori Masaaki , Joers James M. , Kamiya Kouhei , Karbasforoushan Haleh , Keřkovský Miloš , Khatibi Ali , Kim Joo-won , Kinany Nawal , Kitzler Hagen , Kolind Shannon , Kong Yazhuo , Kudlička Petr , Kuntke Paul , Kurniawan Nyoman D. , Kusmia Slawomir , Laganà Maria Marcella , Laule Cornelia , Law Christine S. W. , Leutritz Tobias , Liu Yaou , Llufriu Sara , Mackey Sean , Martin Allan R. , Martinez-Heras Eloy , Mattera Loan , O’Grady Kristin P. , Papinutto Nico , Papp Daniel , Pareto Deborah , Parrish Todd B. , Pichiecchio Anna , Prados Ferran , Rovira Àlex , Ruitenberg Marc J. , Samson Rebecca S. , Savini Giovanni , Seif Maryam , Seifert Alan C. , Smith Alex K. , Smith Seth A. , Smith Zachary A. , Solana Elisabeth , Suzuki Yuichi , Tackley George W , Tinnermann Alexandra , Valošek Jan , Van De Ville Dimitri , Yiannakas Marios C. , Weber Kenneth A. , Weiskopf Nikolaus , Wise Richard G. , Wyss Patrik O. , Xu Junqian , Cohen-Adad Julien , Lenglet Christophe , Nestrašil Igor 
Published: May 2024

Clinical research emphasizes the implementation of rigorous and reproducible study designs that rely on between-group matching or controlling for sources of biological variation such as subject’s sex and age. However, corrections for body size (i.e. height and weight) are mostly lacking in clinical neuroimaging designs. This study investigates the importance of body size parameters in their relationship with spinal cord (SC) and brain magnetic resonance imaging (MRI) metrics. Data were derived from a cosmopolitan population of 267 healthy human adults (age 30.1±6.6 years old, 125 females). We show that body height correlated strongly or moderately with brain gray matter (GM) volume, cortical GM volume, total cerebellar volume, brainstem volume, and cross-sectional area (CSA) of cervical SC white matter (CSA-WM; 0.44≤r≤0.62). In comparison, age correlated weakly with cortical GM volume, precentral GM volume, and cortical thickness (-0.21≥r≥-0.27). Body weight correlated weakly with magnetization transfer ratio in the SC WM, dorsal columns, and lateral corticospinal tracts (-0.20≥r≥-0.23). Body weight further correlated weakly with the mean diffusivity derived from diffusion tensor imaging (DTI) in SC WM (r=-0.20) and dorsal columns (-0.21), but only in males. CSA-WM correlated strongly or moderately with brain volumes (0.39≤r≤0.64), and weakly with precentral gyrus thickness and DTI-based fractional anisotropy in SC dorsal columns and SC lateral corticospinal tracts (-0.22≥r≥-0.25). Linear mixture of sex and age explained 26±10% of data variance in brain volumetry and SC CSA. The amount of explained variance increased at 33±11% when body height was added into the mixture model. Age itself explained only 2±2% of such variance. In conclusion, body size is a significant biological variable. Along with sex and age, body size should therefore be included as a mandatory variable in the design of clinical neuroimaging studies examining SC and brain structure.