Behavior Problems After Early Life Stress: Contributions of the Hippocampus and Amygdala

Abstract:

Background

Early life stress (ELS) can compromise development, with higher amounts of adversity linked to behavior problems. To understand this linkage, a growing body of research has examined two brain regions involved with socio-emotional functioning- the amygdala and hippocampus. Yet empirical studies have reported increases, decreases, and also no differences within human and non-human animal samples exposed to different forms of ELS. Divergence in findings may stem from methodological factors and/or non-linear effects of ELS.

Methods

We completed rigorous hand-tracing of the amygdala and hippocampus in three samples of children who suffered different forms of ELS (i.e., physical abuse, early neglect, or low SES). In addition, interview-based measures of cumulative life stress were also collected with children and their parents or guardians. These same measures were also collected in a fourth sample of comparison children who had not suffered any of these forms of ELS.

Results

Smaller amygdala volumes were found for children exposed to these different forms of ELS. Smaller hippocampal volumes were also noted for children who suffered physical abuse or from low SES-households. Smaller amygdala and hippocampal volumes were also associated with greater cumulative stress exposure and also behavior problems. Hippocampal volumes partially mediated the relationship between ELS and greater behavior problems.

Conclusions

This study suggests ELS may shape the development of brain areas involved with emotion processing and regulation in similar ways. Differences in the amygdala and hippocampus may be a shared diathesis for later negative outcomes related to ELS.