AUTHOR=Han Kihwan , Chapman Sandra B. , Krawczyk Daniel C. 

TITLE=Altered Amygdala Connectivity in Individuals with Chronic Traumatic Brain Injury and Comorbid Depressive Symptoms

JOURNAL=Frontiers in Neurology

VOLUME=Volume 6 - 2015

YEAR=2015

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2015.00231

DOI=10.3389/fneur.2015.00231

ISSN=1664-2295

ABSTRACT=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 (eight 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 (pvoxel<0.01, pcluster<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 (pvoxel<0.01, pcluster<0.025). Taken together, these results suggest that amygdala connectivity may be a potentially effective neuroimaging biomarker for comorbid depressive symptoms in chronic TBI.