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|Title:||NEUROANATOMICAL CORRELATES OF NEUROTICISM AND EXTRAVERSION IN HEALTHY ADOLESCENTS|
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|Authors/Affiliations:||2 Udi Blankstein*; 2 Jerry Chen; 1 Adina Mincic; 1 Karen Davis; |
1 University Health Network, Toronto, ON, Canada; 2 University of Toronto, ON, Canada.
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|Content:||Objectives: Converging evidence from behavioural, psychological and functional brain imaging studies point to a link between specific personality traits (e.g., neuroticism, extraversion) and certain mental disorders (e.g., depression) and chronic pain states; suggesting that there may be a predisposition to these disorders. Furthermore, sex differences exist in the incidence of some psychiatric disorders and chronic pains. Recent studies in healthy adults and patient populations, suggest a relationship between personality traits and functional anatomy in cortical areas, including prefrontal regions. However, little is known about the neuro-maturational processes in the adolescent brain. Therefore, the aim of this study was to investigate the neuroanatomical correlates of neuroticism and extraversion in healthy male and female adolescents. |
Materials and Methods: Thirty-five right-handed healthy adolescents (20 females, 15 males) aged 16-17 years old were recruited from the local population and consented to the study approved by the local research ethics board. Personality measures were assessed with the NEO-FFI prior to brain imaging. Subjects then underwent structural MRI scanning on a 3T GE scanner, 8 channel phased array head coil. A T1-weighted 3D FSPGR anatomical scan (repetition time = 11.8ms, echo time = 5.2ms, flip angle 20º) acquired 120 1.5-mm-thick sagittal slices (FOV=24cm, 256 x 256 matrix). Preprocessing and analysis of images was done using statistical parametric mapping software (SPM5; Wellcome Department of Imaging Neuroscience, Institute of Neurology, London, UK) in MATLAB 7.0.1 (Mathworks, MA). Voxel based Morphometry (VBM) was implemented using tissue segmentation, normalization, 10mm FWHM smoothing, modulation and voxelwise multiple regression with an absolute threshold mask of 0.20 and total intracranial volumes entered as a covariate to control for between subject variance of gross brain size. The statistical threshold was set to p<0.001 with an extent of k>50 voxels.
Results: Neuroticism and extraversion scores were normally distributed and not significantly different between males and females (p = 0.24 and p = 0.11, respectively). The most prominent relationship between gray matter density and neuroticism was a negative correlation localized to the bilateral subgenual anterior cingulate cortex (ACC) (Brodmann area 25) in males only (t = 4.24). Interestingly, the left medial frontal gyrus/rostral ACC (Brodmann area 10/32) was found to be negatively correlated to extraversion in females (t = 4.19) but positively correlated in males (t = 4.32).
Conclusion: These data reveal sex differences in the relationship between the personality traits of neuroticism and extraversion and gray matter density in cingulate and prefrontal cortical regions. These findings raise the issue of whether neuroanatomical correlates of personality traits are sustained over the lifespan. Future studies should assess whether such relationships represent a risk factor for chronic pains and mental disorders such as depression.
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