Maltreatment Exposure, Brain Structure, and Fear Conditioning in Children and Adolescents

Abstract

Alterations in learning processes and the neural circuitry that supports fear conditioning and extinction represent mechanisms through which trauma exposure might influence risk for psychopathology. Few studies examine how trauma or neural structure relates to fear conditioning in children. Children (n=94) aged 6-18 years, 40.4% (n=38) with exposure to maltreatment (physical abuse, sexual abuse, or domestic violence), completed a fear conditioning paradigm utilizing blue and yellow bells as conditioned stimuli (CS+/CS-) and an aversive alarm noise as the unconditioned stimulus. Skin conductance responses (SCR) and self-reported fear were acquired. Magnetic resonance imaging data were acquired from 60 children. Children without maltreatment exposure exhibited strong differential conditioning to the CS+ vs CS-, based on SCR and self-reported fear. In contrast, maltreated children exhibited blunted SCR to the CS+ and failed to exhibit differential SCR to the CS+ vs CS- during early conditioning. Amygdala and hippocampal volume were reduced among children with maltreatment exposure and were negatively associated with SCR to the CS+ during early conditioning in the total sample, although these associations were negative only among non-maltreated children and were positive among maltreated children. The association of maltreatment with externalizing psychopathology was mediated by this perturbed pattern of fear conditioning. Child maltreatment is associated with failure to discriminate between threat and safety cues during fear conditioning in children. Poor threat-safety discrimination might reflect either enhanced fear generalization or a deficit in associative learning, which may in turn represent a central mechanism underlying the development of maltreatment-related externalizing psychopathology in children.

Beyond Cumulative Risk

“…Recent work from our labs is consistent with this prediction, finding atypical fear conditioning among children who experienced environmental threats, including abuse and domestic violence. Children exposed to threat demonstrate poor discrimination of threat and safety cues during fear-conditioning (McLaughlin et al, in press). Whereas children without adversity exposure exhibit stronger fear responses to a stimulus paired with threat compared to one paired with safety, children exposed to threat exhibit fear responses of similar magnitude to threat and safety cues (McLaughlin et al, in press), reflecting either generalization of fear to the safety cue or a generalized problem with associative learning.…”

Extinction learning in childhood anxiety disorders, obsessive compulsive disorder and post-traumatic stress disorder: implications for treatment

“…Across studies, differential conditioning has been observed in these groups of youth [81-83], with some differences emerging for maltreated youth and those with PTSD. Youth who experienced maltreatment exhibited slower differential conditioning as evidenced by a blunted SCR to the CS+ [83]. Additionally, youth with PTSD did not exhibit a differential conditioned SCR when compared to youth without PTSD [83].…”

“…Youth who experienced maltreatment exhibited slower differential conditioning as evidenced by a blunted SCR to the CS+ [83]. Additionally, youth with PTSD did not exhibit a differential conditioned SCR when compared to youth without PTSD [83]. In contrast, another study found PTSD symptom severity to have a small-to-moderate association with larger SCRs to the CS+ [82].…”

“…Boys from a highly trauma-exposed population were found to exhibit greater differential conditioning, compared to girls [82], and younger children exhibited poorer discrimination between CS+ and CS-, compared to older youth [81]. When examining the neurobiology of threat conditioning within this population, findings suggested that the amygdala and hippocampus volume were negatively associated with SCR and/or SR fear to the CS+ during early conditioning, but that the ventromedial prefrontal cortex thickness was positively associated with SR fear to the CS- [83]. To date, there has been no examination of threat generalization or context conditioning among youth with PTSD, trauma exposure, and/or maltreatment.…”

“…Extinction learning was observed across groups of youth with PTSD, trauma exposure, and/or maltreatment for psychophysiological [81,83], but not for SR [83], measures. Additionally, younger children with high anxiety showed reduced FPS to the CS+ [81].…”