Presentation Abstract

Program#/Poster#: 192.07/UU35
Presentation Title: Larger waists linked to smaller brains: Decreased gray matter volume in overweight and obese individuals
Location: Hall A-C
Presentation time: Sunday, Nov 13, 2011, 10:00 AM -11:00 AM
Authors: *D. G. SMITH1, P. S. JONES2, E. T. BULLMORE1,2,3, T. W. ROBBINS1, K. D. ERSCHE1,2;
1Behavioural and Clin. Neurosci. Inst., 2Dept. of Psychiatry, Univ. of Cambridge, Cambridge, United Kingdom; 3Clin. Unit Cambridge, GlaxoSmithKline, Cambridge, United Kingdom
Abstract: The negative impact of obesity on health and neurophysiology are well documented in the scientific literature. However, a new MRI gray matter analysis shows that regional decreases in cortical volume in overweight individuals can occur at a much lower BMI than previously identified. A preliminary analysis of 58 individuals ranging from underweight to obese shows evidence of a significant decrease in gray matter volume in the frontal cortex as BMI increases. BMI scores were used as regressors in a gray matter voxel-based morphometry (VBM) study, processed using FSL-VBM and statistically analyzed using CamBA software. A significant negative correlation between BMI and gray matter volume (p > .001) was seen in 14 frontal cortex regions, with maximum clusters in the left middle orbitofrontal cortex and right gyrus rectus.
Follow-up analyses were conducted, dividing subjects into groups of normal weight (n = 25, BMI = 22.6) and overweight or obese individuals (n = 33, BMI = 27.8). Groups differed significantly on BMI (t = -9.57, p < .001), but not on gender, age, IQ or years of education. Whole brain gray matter volume was compared between the groups and differences were found in three significant clusters (p < .001). Overweight individuals showed significant decreases in gray matter volume in the right anterior cingulum, left middle occipital lobe and left inferior frontal gyrus. In the frontal cortex, there was an overlap in loss of volume in overweight subjects between the two analyses in six areas, including the left superior and middle frontal gyri.
These frontal regions are known to be involved in inhibition and delay discounting, suggesting that overweight individuals may have a problem with impulse control and future planning. As such, additional analyses were performed using self-report measures of impulsivity and inhibition (BIS-11), as well as behavioral tasks assessing motor inhibition and sustained attention. No significant relationships were found between the decrease in cortical volume and task performance, however a correlation between BMI and attentional accuracy approached significance. Additionally, the BIS attention subscale approached significance when negatively correlated with frontal pole volume loss. This suggests a trend towards decreased attentional capacity in obese and overweight individuals, potentially stemming from a loss in cortical gray matter.
Importantly, we do not know whether this gray matter loss is a predating factor in future weight gain or follows from an increase in adipose tissue. It would also be beneficial to determine the impact of these structural decreases on individual traits and behavior.
Disclosures:   D.G. Smith: Other Research Support; Cambridge Overseas Trust. P.S. Jones: Research Grant; Medical Research Council. E.T. Bullmore: Employment; GlaxoSmithKline. T.W. Robbins: Consultant/Advisory Board; GlaxoSmithKline, Cambridge Cognition. K.D. Ersche: Research Grant; Medical Research Council.
Keyword(s): OBESITY
FRONTAL CORTEX
MRI
Support: GlaxoSmithKline RG45422
[Authors]. [Abstract Title]. Program No. XXX.XX. 2011 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2011. Online.

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