(The) effects of emotional trauma on the development of frontolimbic networks

Abstract

Previous studies with adult participants reported an association of depressive disorder and structural al-teration of frontolimbic brain regions in subjects with emotional abuse experiences during childhood and ado-lescence. The results suggest that aberrant function of the frontolimbic circuit and its relation with psychiatric symptoms can be found in adolescents with preclinical status. However, studies focused on functional and structural changes during adolescence are strikingly lacking. In our study, we investigated functional changes of frontolimbic networks during 1) implicit negative emotional word processing and 2) face processing and their relationships with depressive symptoms in adoles-cents with previous verbal abuse experiences. Also, 3) structural alterations of hippocampus, frontal lobe, hip-pocampus, and white matter in adolescents were evaluated. An emotional Stroop task consisting of swear, negative, positive, and neutral words was performed dur-ing fMRI scan for 23 subjects who were divided into low and high exposure groups to peer verbal abuse. High VA group had a higher depression score, greater left ventrolateral prefrontal cortex (VLPFC) activity, and higher left VLPFC-left hippocampus connectivity in swear word conditions. The VLPFC activity and left VLPFC-left hippocampus connectivity was negatively related to the severity of anxiety and depressive symptoms, respec-tively. Also, a gender discrimination task using emotional faces was designed to induce an implicit level of emotional exposure, and was completed by 31 preclinical adolescents during an fMRI scan. The right amygda-la activity and its functional connectivity with the rostral anterior cingulate cortex (ACC) during implicit pro-cessing of negative emotional faces showed a significant relationship with previous verbal abuse experiences. In high VA group, enhanced right amygdala activity and weakened right amygdala-rostral ACC connectivity were reported. The hierarchical regression analyses showed that their current depressive symptoms were asso-ciated with aberrant functional interaction between the right amygdala activity and right amygdala-rostral ACC connectivity. In structural analysis, volume reduction appeared in hippocampal subfields CA2-3, dentate gyrus-CA4, and subiculum, but not in cortical areas in the group with high exposure to verbal abuse. The increased mean diffusivity of the splenium of the corpus callosum was related to the high verbal abuse score across all sub-jects. The results showing changes in the hippocampal subfields and splenium in adolescents provide evidence of early structural markers of previous verbal abuse experiences. Our results demonstated several verbal abuse-related early brain changes in the frontolimbic networks can be associated with vulnerability or resilience to future mood disorder. These results can provide clues to widen our knowledge regarding how emotional abuse experiences can lead to mood disorders.