The impact of childhood emotional abuse and depressive symptoms on sleep macro-architecture and cortical thickness

Background: Adverse childhood events and especially emotional abuse (EA) is consistently associated with poor psychiatric outcomes in adulthood, with depressive symptoms being one of the most prevalent. Both EA and depression are frequently associated with poorer sleep quality and cortical structural abnormalities. Interestingly, some individuals who experienced early-life EA are resilient against the development of psychiatric illness in adulthood and are believed to possess distinct neurobiology that confer more effective coping mechanisms. Methods: 682 subjects from a population-based cohort underwent polysomnography (PSG), whole-body magnetic resonance imaging (MRI) and completed the Childhood Trauma Questionnaire (CTQ) and Patient Health Questionnaire (PHQ-9). Linear regressions were used to model joint EA and depressive symptoms effects with sleep macro-architecture and cortical thickness; and path analyses were used to investigate mediation effects. Results: Considering depressive symptoms as a product variable with EA (EAxdepression), we observed the strongest effect in EAxdepression with percentage spent in SWS (%SWS), where %SWS increased with EA in nondepressed subjects. We observed increased thicknesses in three cortical regions in emotionally-abused, nondepressed individuals from structural MRI. Mediation analysis demonstrated that %SWS significantly mediated the association of EAxdepression with cortical thickness in two of the three regions. Limitations: We are not able to infer any causal role of sleep in our cross-sectional design. Self-report questionnaires are also subject to recall-bias. Conclusions: Higher regional cortical thicknesses in emotionally-abused, non-depressed individuals can partially be explained by increased %SWS, suggesting a potentially protective role of SWS against brain volume loss associated with EA and depression.