Weight loss reduces head motion: Revisiting a major confound in neuroimaging

Abstract

Head motion during magnetic resonance imaging (MRI) induces image artifacts that affect virtually every brain measure. In parallel, cross-sectional observations indicate a correlation of head motion with age, psychiatric disease status and obesity, raising the possibility of a systematic artifact-induced bias in neuroimaging outcomes in these conditions, due to the differences in head motion. Yet, a causal link between obesity and head motion has not been tested in an experimental design. Here, weshow that a change in body mass index (BMI) (i.e., weight loss after bariatric surgery) systematically decreases head motion during MRI. In this setting, reduced imaging artifacts due to lower head motion might result in biased estimates of neural differences induced by changes in BMI. Overall, our finding urges the need to rigorously control for head motion during MRI to enable valid results of neuroimaging outcomes in populations that differ in head motion due to obesity or other conditions. K E Y W O R D S body mass index, head motion, imaging artifact, neuroimaging, obesity, resting state fMRI

Genetic risk of dementia modifies obesity effects on white matter myelin in cognitively healthy adults

“…We also propose that our findings require replication in a larger sample as the number of participants in the different risk profile subgroups was small. It has recently been observed that head motions are more prominent in obese than normal weighted cohorts (Beyer et al, 2020). In the present study HARDI but not qMT data were corrected for motion artefacts.…”

Inter-individual body mass variations relate to fractionated functional brain hierarchies

“…Indeed, additionally controlling for head motion parameters in our statistical models increased the effect sizes in several networks but reduced effect sizes in the frontoparietal network. A prior study showed weight loss is related to reduced head motion, suggesting a need to assess head motion effects in obesity neuroimaging studies 127 . Further work is needed to identify mediating factors between head motion and body weight, and to determine how to optimally include head motion parameters in BMI/obesity neuroimaging.…”

Effects of bariatric surgery on functional connectivity of the reward and default mode network: a pre-registered analysis

“…Head motion was quantified using mean framewise displacement (mFD) according to Power et al, 2012 and log-transformed for further analysis (logmFD). As pre-registered, we did not exclude anybody based on high average head motion (Beyer et al, 2020).…”

“…Further, while higher BMI has been consistently associated with more head motion during rsfMRI (Beyer et al, 2017;Hodgson et al, 2016), previous studies in bariatric surgery patients have not taken this important confounder of FC into account. In the present sample, we previously reported a group-by-time interaction on head motion (Beyer et al, 2020). Thus, we aimed to rigorously control for motion-related variance in our analyses.…”