Community violence exposure in early adolescence: Longitudinal associations with hippocampal and amygdala volume and resting state connectivity

Abstract

Community violence exposure is a common stressor, known to compromise youth cognitive and emotional development. In a diverse, urban sample of 22 adolescents, participants reported on community violence exposure (witnessing a beating or illegal drug use, hearing gun shots, or other forms of community violence) in early adolescence (average age 12.99), and underwent a neuroimaging scan 3-5 years later (average age 16.92). Community violence exposure in early adolescence predicted smaller manually traced left and right hippocampal and amygdala volumes in a model controlling for age, gender, and concurrent community violence exposure, measured in late adolescence. Community violence continued to predict hippocampus (but not amygdala) volumes after we also controlled for family aggression exposure in early adolescence. Community violence exposure was also associated with stronger resting state connectivity between the right hippocampus (using the manually traced structure as a seed region) and bilateral frontotemporal regions including the superior temporal gyrus and insula. These resting state connectivity results held after controlling for concurrent community violence exposure, SES, and family aggression. Although this is the first study focusing on community violence in conjunction with brain structure and function, these results dovetail with other research linking childhood adversity with smaller subcortical volumes in adolescence and adulthood, and with altered frontolimbic resting state connectivity. Our findings suggest that even community-level exposure to neighborhood violence can have detectable neural correlates in adolescents.

Reduced Hippocampal and Amygdala Volumes as Mechanisms of Stress Sensitization to Depression following Childhood Violence Exposure

“…Our findings are consistent with prior studies examining the relation between threat exposure and hippocampal and amygdala volumes in pediatric samples (6,27,28). Although neither hippocampal nor amygdala volumes were associated with depression, both moderated the association between stressful life events and depression, such that this relationship was significantly stronger among youths with smaller hippocampal and amygdala volumes.…”

“…No manual edits were performed on subcortical segmentations. Given, that there is no consistent pattern of lateralization in findings of the relation between childhood violence exposure and hippocampal or amygdala volume (6,27,28), and to reduce multiple comparisons, right and left volumes were summed to create measures of bilateral hippocampal and bilateral amygdala volume. To keep variables on a similar scale for regression analyses, hippocampal and amygdala volumes were all divided by 1,000, and intracranial volumes were divided by 100,000.…”

Reduced hippocampal and amygdala volume as a mechanism underlying stress sensitization to depression following childhood trauma

“…Solid lines indicate significant relations. Dotted lines indicate nonsignificant relations volume in children and adolescents (Hanson et al, 2015;McLaughlin et al, 2016;Saxbe et al, 2018 McLaughlin et al, 2016;Trotman, Gianaros, Zanten, van Williams, & Ginty, 2019;Yang et al, 2008).…”

“…No manual edits were performed on subcortical segmentations. Given that there is no consistent pattern of lateralization in the association of childhood violence exposure with hippocampal or amygdala volume(Hanson et al, 2015;McLaughlin et al, 2016;Saxbe et al, 2018), and to reduce multiple comparisons, right and left volumes were summed to create bilateral hippocampal, amygdala, and thalamus volume measures. To keep variables on a similar scale for regression analyses, subcortical volumes were all divided by 1,000, and intracranial volumes were divided by 100,000.…”

Decomposing complex links between the childhood environment and brain structure in school-aged youth

“…Specifically, male adolescents who had positive caregivers demonstrated relatively increased cortical thinning in dorsofrontal and orbitofrontal cortices compared to those who did not have supportive caregivers and were also living in disadvantaged neighborhoods (Whittle et al, 2017). Exposure to community violence has been associated with decreased gray matter volumes in adolescence (Butler et al, 2018;Saxbe et al, 2018), but less is known about perceptions of neighborhood safety and brain structure. Our findings extend previous work to demonstrate that the neural correlates of caregiving and neighborhood safety may go beyond changes in specific brain regions and involve global shifts in cortical thickness.…”