## 3 Results
### Associations between Current Dixxin Exposure (Indicated by Blood Dixins) and Brain Volume
#### 3.2.2 VBM Analyses; Brain Regions in Which Gray Matter Volume Correlated with Blood Dioxin Levels  
Regions with low gray matter volume (inverse correlations) and high gray matter volume (positive correlations) in association with high dioxin exposure are shown in Table 3 and Figures 1-3. Figure 1 shows an example of inverse correlation between the voxel values of the left fusiform gyrus at [\(-27\) (x), \(8\) (y), \(-47\) (z)] and blood TCDD levels (see below for the details).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Characteristics** & **Mean, [\(n\)]** & **SD, (\%)** & **Min** & **Max** \\ \hline Age (years) & 35.5 & 5.9 & 25.3 & 49 \\ Education (years) & 11.9 & 3.1 & 1 & 16 \\ Smoking & [15] & (46.9) & & \\ Alcohol consumption & [26] & (81.3) & & \\ Weight (kilogram) & 66.3 & 9.4 & 46 & 81.2 \\ Height (cm) & 165.5 & 5.0 & 154 & 178 \\ BMI & 24.2 & 3.0 & 17.1 & 28.2 \\ Right hand dominant & [28] & (87.5) & & \\ Length of residency (years) & 22.1 & 14.6 & 1 & 44 \\ Used herbicides & [10] & (31.3) & & \\ Worked nearby industrial park & [15] & (46.9) & & \\ Job (\% of jobs related to the airbase) & [5] & (15.6) & & \\ Their mothers lived in Bien Hoa during pregnancy & [12] & (37.5) & & \\ \hline \hline \end{tabular} \(n\): number of subjects; SD: standard deviation; BMI: body mass index.  
\end{table}
Table 2: Characteristics of the subjects (\(n=32\)).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Dioxin Congeners** & **Brain Regions** & **No of Voxels in** & **Peak Z** & \multicolumn{3}{c}{**MNi Coordinates**} \\  & & **Each Cluster (k)** & **Scores** & **x** & **y** & **z** \\ \hline Inverse correlations & & & & & & \\ TCDD & Anterior temporal cortex & 905 & & & & \\  & (Left medial temporal pole) & & 3.81 & \(-41\) & 20 & \(-38\) \\  & (Left fusiform gyrus) & & 3.90 & \(-27\) & 8 & \(-47\) \\ TEQ-PCDDs & Left medial temporal pole & 333 & 3.63 & \(-39\) & 21 & \(-38\) \\ Positive correlations & & & & & \\
1,2,3,4,7,8-HxCDD & Left cerebellum lobule VII & 373 & 3.87 & \(-42\) & \(-60\) & \(-57\) \\  & Right middle frontal gyrus & 505 & 3.86 & 41 & 6 & 60 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Brain regions significantly correlated with blood levels of dioxin congeners in men after adjusting for total intracranial volume and age (FDR-corrected at \(p<0.05\)).  
Volume in the anterior temporal cortex including the left medial temporal pole and fusiform gyrus showed significant inverse correlations with TCDD (\(p<0.05\), FDR-corrected; Table 3, Figure 2A). The left medial temporal pole was significantly inversely correlated with TEQ-PCDDs (\(p<0.05\), FDR-corrected; Table 3, Figure 2B). In contrast, the left cerebellum and right middle frontal gyrus volume were significantly positively correlated with 1,2,3,4,7,8-HxCDD exposure (\(p<0.05\), FDR-corrected; Table 3, Figure 3).  
Figure 1: Relationships between the voxel values of the left fusiform gyrus at \([-27\) (x), \(8\) (y), \(-47\) (z)], and blood TCDD levels in the 32 subjects. There was a significant and inverse correlation between the two parameters after adjusting for total intracranial volume and age of the subjects.  
Figure 2: Brain regions showing significant negative correlations with blood levels of TCDD (**A**) and TEQ-PCDDs (**B**) (FDR-corrected at \(p<0.05\)) are indicated by yellow color and arrows on axial MRI. (**A**) shows the correlations in the left medial temporal pole (arrows without *) and fusiform gyrus (an arrow with *) and (**B**) shows those in the left medial temporal pole (arrows). L and R indicate the left and right sides of the hemispheres, respectively. Each value below each brain slice indicates each value in MNI z-coordinates.  
Comparisons of Global and Regional Brain Volumes between Men with and without Possible Perinatal Dixxin Exposure