Socioeconomic Disadvantage Moderates the Association of Systemic Inflammation With Amygdala Volume in Adolescents Over a 2-Year Interval: An Exploratory Study.

Background: Research has demonstrated an association between elevated systemic inflammation and changes in brain function. Affective areas of the brain involved in processing threat (e.g., amygdala) and reward (e.g., nucleus accumbens) appear to be sensitive to inflammation. Early-life stress, such as experiencing low socioeconomic status (SES), may also potentiate this association, but relevant evidence has come primarily from cross-sectional studies of brain function. It is unclear whether similar associations are present between early-life stress, inflammation, and brain structure, particularly in typically developing populations.

Methods: We recruited and assessed 50 adolescents (31 females/19 males) from the community (mean [SD] age = 15.5 [1.1] years, range = 13.1-17.5 years) and examined in exploratory analyses whether changes in C-reactive protein (ΔCRP) from blood spots predict changes in gray matter volume (ΔGMV) in the bilateral amygdala and nucleus accumbens over a 2-year period. We also investigated whether experiencing early-life stress, operationalized using a comprehensive composite score of SES disadvantage at the family and neighborhood levels, significantly moderated the association between ΔCRP and ΔGMV.

Results: We found that ΔCRP was negatively associated with Δamygdala GMV (i.e., increasing CRP levels were associated with decreasing amygdala volume; β = -0.84, p = .012). This effect was stronger in youths who experienced greater SES disadvantage (β = -0.56, p = .025).

Conclusions: These findings suggest that increases in systemic inflammation are associated with reductions in amygdala GMV in adolescents, potentially signaling accelerated maturation, and that these neuroimmune processes are compounded in adolescents who experienced greater SES disadvantage. Our findings are consistent with theoretical frameworks of neuroimmune associations and suggest that they may influence adolescent neurodevelopment.