Methods: The current study followed the PRISMA guideline. Inclusion criteria includes: peer-reviewed studies reporting associations between CM and hippocampus or amygdala volumes, written in English and published between 1997 and 2017. The search was conducted in PsycINFO, Medline, and SSCI, and 20 articles were selected. Cohen’s d was extracted for effect size. MetaSEM package in R (Cheung, 2015) was used for analysis in which a random-effect model in a 3-level meta-analysis framework was constructed. Univariate regression modeling was used to test effects of moderators including laterality, gender, race, CM types, and age.
Results: Results yielded a significantly negative effect size for hippocampus (d = -.76, p < .01, 95%CI [-1.30, -.23]). A significant Q statistic (Q (62) =774.51, p < .001) indicated heterogeneity among the effect sizes. A large I2 (.97) at the third level (the study level) and a small I2 (<.001) at the second level (within each study) indicated that the heterogeneity can be accounted mainly by the differences of studies. Moderation analysis suggested that those physically abused individuals exhibited smaller volume of hippocampus (B = -.16, p <.05). Fail-safe N indicators (N1 = 5332.01; N+ = 5543.01) suggested that the publication bias in the current study can be “safely ignored.” For amygdala, results suggested a non-significant mean effect size (d = -.35, p = .12, 95%CI [-.79, .09]). A significant Q statistic (Q (19) =106.641, p <.001) indicated heterogeneity among the effect sizes. A large I2 (.88) at the third level and a small I2 (<.001) at the second level indicated that the heterogeneity can be accounted for mainly by the differences of studies. Moderator analyses revealed no lateral, age, or gender differences.
Conclusions: Child maltreatment is associated with structural changes in the brain that are in turn associated with risks such as alcoholism (De Bellis et al. 2000; Hill et al. 2001). Preventive intervention programs can be designed to address neurobiological impacts of child maltreatment in order to mitigate the sequela of CM.