Neuroticism, depressive symptoms and white-matter integrity in the Lothian Birth Cohort 1936.
BACKGROUND
Clinical depression is associated with reductions in white-matter integrity in several long tracts of the brain. The extent to which these findings are localized or related to depressive symptoms or personality traits linked to disease risk remains unclear. Method Members of the Lothian Birth Cohort 1936 (LBC936) were assessed in two waves at mean ages of 70 and 73 years. At wave 1, they underwent assessments of depressive symptoms and the personality traits of neuroticism and extraversion. Brain diffusion magnetic resonance imaging (MRI) data were obtained at the second wave and mood assessments were repeated. We tested whether depressive symptoms were related to reduced white-matter tract fractional anisotropy (FA), a measure of integrity, and then examined whether high neuroticism or low extraversion mediated this relationship.


RESULTS
Six hundred and sixty-eight participants provided useable data. Bilateral uncinate fasciculus FA was significantly negatively associated with depressive symptoms at both waves (standardized β=0.12-0.16). Higher neuroticism and lower extraversion were also significantly associated with lower uncinate FA bilaterally (standardized β=0.09-0.15) and significantly mediated the relationship between FA and depressive symptoms.


CONCLUSIONS
Trait liability to depression and depressive symptoms are associated with reduced structural connectivity in tracts connecting the prefrontal cortex with the amygdala and anterior temporal cortex. These effects suggest that frontotemporal disconnection is linked to the etiology of depression, in part through personality trait differences.
Division of Psychiatry, University of Edinburgh, UK. andrew.mcintosh@ed.ac.uk
A M
AM
McIntosh
M E
ME
Bastin
M
M
Luciano
S Muñoz
SM
Maniega
M
M
Del C Valdés Hernández
N A
NA
Royle
J
J
Hall
C
C
Murray
S M
SM
Lawrie
J M
JM
Starr
J M
JM
Wardlaw
I J
IJ
Deary
D000368:Aged; D016880:Anisotropy; D001008:Anxiety Disorders / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D015331:Cohort Studies; D003337:Corpus Callosum / Q000473:pathology; D003863:Depression / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005120:Extraversion, Psychological; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology; D006801:Humans; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology; D000075384:Neuroticism