No Alterations of Brain Structural Asymmetry in Major Depressive Disorder: An ENIGMA Consortium Analysis
Authors: Carolien G.F. de Kovel, Lyubomir Aftanas, André Aleman, Aaron F. Alexander-Bloch, Bernhard T. Baune, Ivan Brack, Robin Bülow, Geraldo Busatto Filho, Angela Carballedo, Colm G. Connolly, Kathryn R. Cullen, Udo Dannlowski, Christopher G. Davey, Danai Dima, Katharina Dohm, Tracy Erwin-Grabner, Thomas Frodl, Cynthia H.Y. Fu, Geoffrey B. Hall, David C. Glahn, Beata Godlewska, Ian H. Gotlib, Roberto Goya-Maldonado, Hans Jörgen Grabe, Nynke A. Groenewold, Dominik Grotegerd, Oliver Gruber, Mathew A. Harris, Ben J. Harrison, Sean N. Hatton, Ian B. Hickie, Tiffany C. Ho, Neda Jahanshad, Tilo Kircher, Bernd Krämer, Axel Krug, Jim Lagopoulos, Elisabeth J. Leehr, Meng Li, Frank P. MacMaster, Glenda MacQueen, Andrew M. McIntosh, Quinn McLellan, Sarah E. Medland, Bryon A. Mueller, Igor Nenadic, Evgeny Osipov, Martina Papmeyer, Maria J. Portella, Liesbeth Reneman, Pedro G.P. Rosa, Matthew D. Sacchet, Knut Schnell, Anouk Schrantee, Kang Sim, Egle Simulionyte, Lisa Sindermann, Aditya Singh, Dan J. Stein, Benjamin N. Ubani, Nic J.A. Van der Wee, Steven J.A. Van der Werff, Ilya M. Veer, Yolanda Vives-Gilabert, Henry Völzke, Henrik Walter, Martin Walter, Melinda Westlund Schreiner, Heather Whalley, Nils Winter, Katharina Wittfeld, Tony T. Yang, Dilara Yüksel, Dario Zaremba, Paul M. Thompson, Dick J. Veltman, Lianne Schmaal, Clyde Francks
Journal: American Journal of Psychiatry (2019)

Objective: Asymmetry is a subtle but pervasive aspect of the human brain, and it may be altered in several psychiatric conditions. MRI studies have shown subtle differences of brain anatomy between people with major depressive disorder and healthy control subjects, but few studies have specifically examined brain anatomical asymmetry in relation to this disorder, and results from those studies have remained inconclusive. At the functional level, some electroencephalography studies have indicated left fronto-cortical hypoactivity and right parietal hypoactivity in depressive disorders, so aspects of lateralized anatomy may also be affected. The authors used pooled individual-level data from data sets collected around the world to investigate differences in laterality in measures of cortical thickness, cortical surface area, and subcortical volume between individuals with major depression and healthy control subjects. Methods: The authors investigated differences in the laterality of thickness and surface area measures of 34 cerebral cortical regions in 2,256 individuals with major depression and 3,504 control subjects from 31 separate data sets, and they investigated volume asymmetries of eight subcortical structures in 2,540 individuals with major depression and 4,230 control subjects from 32 data sets. T1-weighted MRI data were processed with a single protocol using FreeSurfer and the Desikan-Killiany atlas. The large sample size provided 80% power to detect effects of the order of Cohen's d=0.1. Results: The largest effect size (Cohen's d) of major depression diagnosis was 0.085 for the thickness asymmetry of the superior temporal cortex, which was not significant after adjustment for multiple testing. Asymmetry measures were not significantly associated with medication use, acute compared with remitted status, first episode compared with recurrent status, or age at onset. Conclusions: Altered brain macro-anatomical asymmetry may be of little relevance to major depression etiology in most cases.