The enduring impact of childhood maltreatment on grey matter development

Childhood maltreatment doubles an individual’s risk of developing a psychiatric disorder, yet the neurobiological nature of the enduring impact of childhood maltreatment remains elusive. This thesis explores the long-term effect of childhood maltreatment on grey matter. The primary aims of this thesis are to discern the spatial extent, temporal profile and physiological breadth of the developmental impact of childhood maltreatment amongst young people with emerging mental disorder. Chapter II comprises of a meta-analysis of thirty-eight published articles and demonstrates that adults with a history of childhood maltreatment most commonly exhibit reduced grey matter in the hippocampus, amygdala and right dorsolateral prefrontal cortex, compared to non-maltreated adults. Chapters III-V contain three original studies, involving a cohort of 123 young people, aged 14-26, with emerging mental illness. Chapter III bridges a gap between cross-sectional child and adult studies by longitudinally mapping the developmental trajectory of the hippocampus and amygdala following childhood maltreatment. This study provided the first direct evidence that childhood maltreatment stunts hippocampal development into young adulthood. Chapter IV assesses the utility of the cumulative stress and mismatch hypotheses in understanding the contribution of childhood abuse and recent stress to the structure and function of the limbic system. Chapter V extends on recent advances in connectome research to examine the effect of childhood maltreatment on structural covariance networks. Investigation of the correspondence of structural covariance with structural connectivity and functional connectivity revealed that reduced grey matter across the network is likely related to deceased functional coactivation following childhood maltreatment. Chapter VI discusses the significance of these studies in understanding how maltreatment shapes brain development and increases the risk of psychiatric illness