Increased body mass index is associated with specific regional alterations in brain structure

Abstract

Background:Although obesity is associated with structural changes in brain grey matter, findings have been inconsistent and the precise nature of these changes is unclear. Inconsistencies may partly be due to the use of different volumetric morphometry methods, and the inclusion of participants with comorbidities that exert independent effects on brain structure. The latter concern is particularly critical when sample sizes are modest. The purpose of the current study was to examine the relationship between cortical grey matter and body mass index (BMI), in healthy participants, excluding confounding comorbidities and using a large sample size.Subjects:A total of 202 self-reported healthy volunteers were studied using surface-based morphometry, which permits the measurement of cortical thickness, surface area and cortical folding, independent of each other.Results:Although increasing BMI was not associated with global cortical changes, a more precise, region-based analysis revealed significant thinning of the cortex in two areas: left lateral occipital cortex (LOC) and right ventromedial prefrontal cortex (vmPFC). An analogous region-based analysis failed to find an association between BMI and regional surface area or folding. Participants' age was also found to be negatively associated with cortical thickness of several brain regions; however, there was no overlap between the age- and BMI-related effects on cortical thinning.Conclusions:Our data suggest that the key effect of increasing BMI on cortical grey matter is a focal thinning in the left LOC and right vmPFC. Consistent implications of the latter region in reward valuation, and goal control of decision and action suggest a possible shift in these processes with increasing BMI.

Increasing Body Mass Index at Midlife is Associated with Increased Cortical Thinning in Alzheimer’s Disease-Vulnerable Regions

“…Increasing BMI at midlife was also associated with atrophy in right lingual gyrus, anterior cingulate, and the peri-calcarine sulcus. A recent cross-sectional study by Medic et al also found a negative association between anterior cingulate thickness and BMI, which they postulated might have relevance for reward evaluation and decision control in obesity [23].…”

Combined effects of age and BMI are related to altered cortical thickness in adolescence and adulthood

“…In the context of the obesity pandemic, these findings have spurred neuroimaging research into health-harming weight gain. Structurally, elevated BMI has been consistently related to reduced grey matter (GM) and white matter (WM) integrity in the adult and ageing brain (Kurth et al, 2013;Medic et al, 2019Medic et al, , 2016Pannacciulli et al, 2006;Ronan et al, 2016). However, whether adiposity impacts on the developing brain, particularly during critical periods of accelerated GM and WM changes, remains unknown.…”

“…Elevated BMI (Ho et al, 2010;Raji et al, 2010) and obesity (Gunstad et al, 2009;Yokum et al, 2012) have been associated with reduced total GMV; however, body mass has been consistently unrelated to global mean CT. Local GMV reductions have been observed in the OFC and the anterior cingulate cortex with increasing BMI (Raji et al, 2010), and decreased posterior parietal and temporal volumes have been reported in overweight adults (Gunstad et al, 2009;Walther et al, 2009). Studies examining local CT alterations have primarily shown BMI-related thinning in the left inferior parietal cortex, the inferior temporal and insular cortex (Hassenstab et al, 2012;Veit et al, 2014), and the prefrontal cortex, including ventromedial (Medic et al, 2016), superior frontal and orbitofrontal (Marqués-Iturria et al, 2013) regions. Although the structural correlates of neurocognitive phenotypes in obesity remain poorly characterised, reduced thickness in the superior frontal gyrus has been related to poorer performance on an inhibitory control task and higher BMI (Lavagnino et al, 2016).…”

Inflammatory agents partially explain changes in cortical thickness and surface area related to body mass index in adolescence

“…Our results are highly consistent with studies conducted in adults. Cortical thinning linked to BMI was also described in the left LOC (Medic et al, 2016), as well as in the left inferior parietal cortex, including LOC and fusiform areas, and the right precentral gyrus (Veit et al, 2014). Both studies carried out vertex-wise correlations with a wide range of BMI that included healthy and unhealthy values that are compatible with obesity.…”