Childhood maltreatment correlates with reactivity of amygdala to subliminally presented negative facial expressions
The human amygdala is known to respond to emotional stimuli that are presented subliminally, such as photographs of facial expressions presented so briefly (few tens of milliseconds) that conscious percept of the stimuli fails to take place. Interestingly, hyper-responsiveness of human amygdala to negative facial expressions has been observed in a number of psychiatric conditions including clinical depression, anxiety disorders, and borderline personality. One of the critical questions has been whether these deviations in pre-attentive amygdala responsiveness reflect a trait (caused by for example due to adverse childhood events) that predisposes to psychiatric conditions, or whether the psychiatric conditions (i.e., state) cause the negative processing bias.
In their recent study, Dannlowski et al. (2012) investigated in a sizeable group of healthy volunteers (N=150) whether childhood maltreatment predicts amygdala hyper-responsiveness to subliminally presented negative facial expressions. During functional magnetic resonance imaging, pictures depicting neutral, positive, and negative facial expressions were presented briefly (33 ms) followed immediately by presentation of a neutral facial expression that served as a masker stimulus. The authors assessed childhood maltreatment using childhood trauma questionnaire, which is a retrospective 25-item self-report questionnaire.
As hypothesized by the authors, there was a significant correlation between the childhood trauma questionnaire scores and amygdala hyper-responsiveness to subliminally presented sad facial expressions, which was not confounded by trait anxiety, current depression level, age, gender, intelligence, education level, or recent stressful life-events that the authors carefully controlled. While the authors quite correctly caution that only a prospective study could provide decisive evidence on a causal relationship between childhood maltreatment and pre-attentive amygdala hyper-responsiveness to negative facial expressions, these results nonetheless provide significant evidence for a link between maltreatment in childhood and aberrant automatic processing of negative emotional expressions in adulthood. Importantly, these findings might in part explain how childhood maltreatment predisposes individuals to development of psychiatric conditions, such as clinical depression, later in life.
Reference: Dannlowski U, Kugel H, Huber F, Stuhrmann A, Redlich R, Grotegerd D, Dohm K, Sehlmeyer K, Konrad C, Baune BT, Arolt V, Heindel W, Zwitserlood P, Suslow T. Childhood maltreatment is associated with an automatic negative emotion processing bias in the amygdala. Human Brain Mapping (2012) e-publication ahead of print. http://dx.doi.org/10.1002/hbm.22112