Allostatic load as a mediator of childhood maltreatment and adulthood depressive symptoms: A longitudinal analysis

Childhood maltreatment (CM) is associated with several negative outcomes in adulthood, including major depression. People who experience CM that go on to develop symptoms of major depression in adulthood tend to have earlier depressive symptom onset and greater symptom severity than those who do not experience CM. Studies have utilized allostatic load (AL) to understand how CM "gets under the skin" to contribute to depressive symptoms. However, studies largely utilize cross-sectional designs and limited biomarkers. The present study uses data from Wave 2 and Wave 3 of the Midlife Development in the United States study in regression-based analyses, examining if AL mediates the relationship between CM and the number of depressive symptoms in adulthood. AL was measured at Wave 2 using the system risk method with 27 biomarkers across seven different systems. CM was measured using the Childhood Trauma Questionnaire at Wave 2. Number of depressive symptoms were measured using the Composite International Diagnostic Interview-Short Form at Wave 3. Past month perceived stress, age, household income, education, sex, racial/ethnic identity, and current prescription medication use at Wave 2 were included as controls. Analyses identified that CM was associated with AL cross-sectionally, and that both CM and AL at were associated with the number of depressive symptoms prospectively. AL partially mediated the effects of CM on the number of depressive symptoms. The present study is the first to identify the mediating role of AL in the relationship between CM and adulthood depressive symptoms in a longitudinal design.