Medic N, Ziauddeen H, Ersche K D, Farooqi I S, Bullmore E T, Nathan P J, Ronan L, Fletcher P C
Department of Psychiatry, University of Cambridge, Cambridge, UK.
Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK.
Int J Obes (Lond). 2016 Jul;40(7):1177-82. doi: 10.1038/ijo.2016.42. Epub 2016 Mar 22.
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.
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.
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.
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.
尽管肥胖与脑灰质的结构变化有关，但其研究结果并不一致，这些变化的确切性质尚不清楚。结果不一致可能部分归因于使用了不同的体积形态测量方法，以及纳入了对脑结构有独立影响的合并症患者。当样本量较小时，后一个问题尤为关键。本研究的目的是在排除混杂合并症且样本量较大的健康参与者中，研究皮质灰质与体重指数（BMI）之间的关系。
共有202名自我报告的健康志愿者接受了基于表面的形态测量研究，该方法能够独立测量皮质厚度、表面积和皮质折叠情况。
尽管BMI的增加与整体皮质变化无关，但更精确的基于区域的分析显示，两个区域的皮质显著变薄：左侧枕外侧皮质（LOC）和右侧腹内侧前额叶皮质（vmPFC）。类似的基于区域的分析未发现BMI与区域表面积或折叠之间存在关联。还发现参与者的年龄与几个脑区的皮质厚度呈负相关；然而，年龄和BMI对皮质变薄的影响没有重叠。
我们的数据表明，BMI增加对皮质灰质的关键影响是左侧LOC和右侧vmPFC的局灶性变薄。后一个区域在奖励评估以及决策和行动的目标控制中的持续作用表明，随着BMI的增加，这些过程可能会发生变化。
