Research Reports - Altered amygdala connectivity in individuals with chronic traumatic brain injury and comorbid depressive symptoms
Front Neurol. 2015 Nov 4;6:231. doi: 10.3389/fneur.2015.00231. eCollection 2015.
Han K(1), Chapman SB(1), Krawczyk DC(2).
Depression is one of the most common psychiatric conditions in individuals with
chronic traumatic brain injury (TBI). Though depression has detrimental effects
in TBI and network dysfunction is a "hallmark" of TBI and depression, there have
not been any prior investigations of connectivity-based neuroimaging biomarkers
for comorbid depression in TBI. We utilized resting-state functional magnetic
resonance imaging to identify altered amygdala connectivity in individuals with
chronic TBI (8 years post-injury on average) exhibiting comorbid depressive
symptoms (N = 31), relative to chronic TBI individuals having minimal depressive
symptoms (N = 23). Connectivity analysis of these participant sub-groups revealed
that the TBI-plus-depressive symptoms group showed relative increases in amygdala
connectivity primarily in the regions that are part of the salience, somatomotor,
dorsal attention, and visual networks (p voxel < 0.01, p cluster < 0.025).
Relative increases in amygdala connectivity in the TBI-plus-depressive symptoms
group were also observed within areas of the limbic-cortical mood-regulating
circuit (the left dorsomedial and right dorsolateral prefrontal cortices and
thalamus) and the brainstem. Further analysis revealed that spatially dissociable
patterns of correlation between amygdala connectivity and symptom severity
according to subtypes (Cognitive and Affective) of depressive symptoms (p
voxel < 0.01, p cluster < 0.025). Taken together, these results suggest that
amygdala connectivity may be a potentially effective neuroimaging biomarker for
comorbid depressive symptoms in chronic TBI.