Using high-resolution magnetic resonance imaging and voxel-based morphometry in 41 healthy individuals, this study evaluated the association between the personality traits of extraversion and neuroticism, on the one hand, and individual differences in localized brain volume and gray matter concentration, on the other, with a special focus on the amygdala. Extraversion was positively correlated with gray matter concentration in the left amygdala, whereas neuroticism was negatively correlated with gray matter concentration in the right amygdala. Given that neuroticism is a risk factor for depression, our finding offers one explanation as to why prior structural imaging studies of depressed patients (which did not control for personality) produced conflicting findings. Furthermore, our data are consistent with the view that amygdala reduction seen in depressed patients precedes the onset of the disease, rather than being a consequence of the illness.
aDepartment of Psychology
bGraduate Program in Genetics, Stony Brook University, Stony Brook, New York
cMagnetic Resonance Research Center, Yale University, New Haven, Connecticut, USA
Correspondence and requests for reprints to Turhan Canli, PhD, Graduate Program in Genetics, and Department of Psychology, Stony Brook University, Stony Brook, NY 11794-2500, USA
Sponsorship: This research was supported by Stony Brook University and NSF ♯BCS-0224221.
Received 9 September 2005; revised 14 September 2005; accepted 15 September 2005