Statistical Analyses

Two groups of subjects, normal weight (BMI < 25) and obese (BMI > 30), were assessed for their GM volume values. The voxel-wise two-sample t-tests were performed to compare the group differences in GM volumes. The resulting statistical maps with a significant level of p = 0.005, cluster size > 50 were identified as activations⁵¹. The GM volume values of the significant activations and each ROI (OFC, amygdala and pallidum) were calculated for each subject. To compare structural brain alterations related to impulsive personality traits between the two groups, we used a partial correlation analysis with age, gender and handiness as covariates to analyze the relationship between regional GM volumes of ROIs and the scores of each impulsive personality traits scale (lack of premeditation, lack of perseverance, sensation seeking, negative urgency, and positive urgency). The correlation with a significance of p = 0.010 was further discussed.