Mega-analysis of association between obesity and cortical morphology in bipolar disorders: ENIGMA study in 2832 participants
Authors: McWhinney Sean R. , Abé Christoph , Alda Martin , Benedetti Francesco , Bøen Erlend , del Mar Bonnin Caterina , Borgers Tiana , Brosch Katharina , Canales-Rodríguez Erick J. , Cannon Dara M. , Dannlowski Udo , Diaz-Zuluaga Ana M. , Dietze Lorielle M.F. , Elvsåshagen Torbjørn , Eyler Lisa T. , Fullerton Janice M. , Goikolea Jose M. , Goltermann Janik , Grotegerd Dominik , Haarman Bartholomeus C. M. , Hahn Tim , Howells Fleur M. , Ingvar Martin , Jahanshad Neda , Kircher Tilo T. J. , Krug Axel , Kuplicki Rayus T. , Landén Mikael , Lemke Hannah , Liberg Benny , Lopez-Jaramillo Carlos , Malt Ulrik F. , Martyn Fiona M. , Mazza Elena , McDonald Colm , McPhilemy Genevieve , Meier Sandra , Meinert Susanne , Meller Tina , Melloni Elisa M. T. , Mitchell Philip B. , Nabulsi Leila , Nenadic Igor , Opel Nils , Ophoff Roel A. , Overs Bronwyn J. , Pfarr Julia-Katharina , Pineda-Zapata Julian A. , Pomarol-Clotet Edith , Raduà Joaquim , Repple Jonathan , Richter Maike , Ringwald Kai G. , Roberts Gloria , Ross Alex , Salvador Raymond , Savitz Jonathan , Schmitt Simon , Schofield Peter R. , Sim Kang , Stein Dan J. , Stein Frederike , Temmingh Henk S. , Thiel Katharina , Thomopoulos Sophia I. , van Haren Neeltje E. M. , Vargas Cristian , Vieta Eduard , Vreeker Annabel , Waltemate Lena , Yatham Lakshmi N. , Ching Christopher R. K. , Andreassen Ole A. , Thompson Paul M. , Hajek Tomas ,   for the ENIGMA Bipolar Disorder Working Group
Published: February 2023

Background:

Obesity is highly prevalent and disabling, especially in individuals with severe mental illness including bipolar disorders (BD). The brain is a target organ for both obesity and BD. Yet, we do not understand how cortical brain alterations in BD and obesity interact.

Methods:

We obtained body mass index (BMI) and MRI-derived regional cortical thickness, surface area from 1231 BD and 1601 control individuals from 13 countries within the ENIGMA-BD Working Group. We jointly modeled the statistical effects of BD and BMI on brain structure using mixed effects and tested for interaction and mediation. We also investigated the impact of medications on the BMI-related associations.

Results:

BMI and BD additively impacted the structure of many of the same brain regions. Both BMI and BD were negatively associated with cortical thickness, but not surface area. In most regions the number of jointly used psychiatric medication classes remained associated with lower cortical thickness when controlling for BMI. In a single region, fusiform gyrus, about a third of the negative association between number of jointly used psychiatric medications and cortical thickness was mediated by association between the number of medications and higher BMI.

Conclusions:

We confirmed consistent associations between higher BMI and lower cortical thickness, but not surface area, across the cerebral mantle, in regions which were also associated with BD. Higher BMI in people with BD indicated more pronounced brain alterations. BMI is important for understanding the neuroanatomical changes in BD and the effects of psychiatric medications on the brain.