Altered amygdala connectivity in urban youth exposed to trauma

Abstract

Early life trauma exposure represents a potent risk factor for the development of mental illnesses such as anxiety, depression and post-traumatic stress disorder. Moreover, deleterious consequences of trauma are exacerbated in youth living in impoverished, urban environments. A priori probability maps were used to examine resting-state functional connectivity (FC) of the amygdala in 21 trauma-exposed, and 21 age- and sex-matched urban children and adolescents (youth) without histories of trauma. Intrinsic FC analyses focused on amygdala-medial prefrontal circuitry, a key emotion regulatory pathway in the brain. We discovered reduced negative amygdala-subgenual cingulate connectivity in trauma-exposed youth. Differences between groups were also identified in anterior insula and dorsal anterior cingulate to amygdala connectivity. Overall, results suggest a model in which urban-dwelling trauma-exposed youth lack negative prefrontal to amygdala connectivity that may be critical for regulation of emotional responses. Functional changes in amygdala circuitry might reflect the biological embedding of stress reactivity in early life and mediate enhanced vulnerability to stress-related psychopathology.

Amygdala functional connectivity as a longitudinal biomarker of symptom changes in generalized anxiety

“…Worry induction in elderly GAD participants evoked stronger connectivity between insula and orbitofrontal cortex that diminished during reappraisal (Andreescu et al , 2015). Stronger amygdala-insula functional connectivity is also reported in urban youth exposed to trauma (Thomason et al , 2015) and adults with PTSD (Rabinak et al , 2011), highlighting reproducible involvement of amygdala–insular interaction for anxiety disorders.…”

Stress and the adolescent brain

“…One means of measuring functional connectivity is to employ resting state measures, which assay spontaneous regional interactions that occur when a subject is not performing an explicit task and provides an index of the integrity of a functional connection between regions of interest. Adolescents with a history of child maltreatment (Herringa et al, 2013) or trauma (Pagliaccio et al, 2015; Thomason et al, 2015) exhibit weaker connectivity between amygdala and PFC regions (Nooner et al, 2013), including regions in the medial PFC (mPFC). The nature of amygdala-mPFC resting state connectivity has implications for future mental health; in adulthood, weaker connectivity is associated with increased trait anxiety (Kim, Gee, Loucks, Davis, & Whalen, 2011).…”

Toward understanding the impact of trauma on the early developing human brain

“…Lower connectivity was, in turn, related to self-reported anxiety and depression symptoms, and to elevated childhood cortisol, in females (Burghy et al, 2012). Altered frontoamygdala functional connectivity has also been observed in previously institutionalized children (mean age ± sd = 13.2 ± 5.2 years) while viewing emotional face stimuli (Gee et al, 2013), and urban, trauma-exposed youth (mean age ± sd = 12.6 ± 2.1 years) during resting-state fMRI (see Figure 2; Thomason et al, 2015). …”

“…Changes observed include atypical response to emotional stimuli, reduced hippocampal response during declarative memory retrieval (Carrion et al, 2010), amplified response to stimuli depicting negative emotions (Pollak and Sinha, 2002, McCrory et al, 2011), and altered connectivity in amygdala-prefrontal circuitry (Thomason et al, 2015). Animal studies further elaborate the basis of these observations demonstrating, for example, that animals exposed to chronic restraint stress show reduced dendritic elaboration in hippocampus and medial PFC (mPFC) pyramidal cells (Eiland et al, 2012).…”

“…For instance, in secondary analyses it is possible to isolate main effects that relate to participant characteristics or to confirm whether main effects replicate in subsamples deliberately matched on these characteristics. These strategies have been employed in prior fMRI studies of youth with histories of trauma (Marusak et al, 2015a, Marusak et al, 2015b, Thomason et al, 2015). …”