Longitudinal Test of the Stress Sensitization Hypothesis for Depression in Older Age: Evaluating the Combined Impacts of Childhood Trauma and Recent Stress

Introduction: Older individuals are likely to experience multiple major life stressors with respect to medical, financial and interpersonal circumstances, and experience greater depressive symptomatology from them. The sensitization hypothesis posits that the psychological impact of such stress increases for individuals with a history of childhood trauma. We address limitations of prior studies, using a within-person repeated-measures design to address fluctuations that occur within individuals over time; and studying exogenous stressful events (those unlikely to be caused by the individual) in order to help rule out (a) reverse causation, and (b) stressors that are not etiologically relevant to depressive symptomatology. We hypothesized: (H1) Childhood trauma and recent stress would associate with an increased levels of recent depressive symptoms; (H2) in accordance with the Stress Sensitization Hypothesis, childhood trauma would amplify the effect of recent stress on depressive symptoms.  As evidence suggests that mental health outcomes exhibit greater divergence between ethnic groups in older adults, we examined effects separately by ethnicity.  Methods: Depressive symptoms and recent stress, based on 148,273 observations from 28,248 adults (57% female; baseline mean age=63, range 50-104 years; 81% Non-Hispanic White (NHW), 15% Hispanic-Latino (HL), 5% African-American (AA)), were obtained biannually in the Health and Retirement Study, a U.S. population-based study of adults age 50+. Depressive symptoms were assessed with a modified Center for Epidemiologic Studies Depression (CESD) scale. Recent exogenous stressors included divorce, loss of a spouse, disability, cancer or other diagnosis, financial shock occurring in the two years prior to each CESD assessment. Childhood trauma, available for N=16,698, included parent loss, abuse and neglect prior to age 18. Ordered logit models were constructed to test hypotheses, adjusted for age and sex, stratified by ethnicity.  Results: H1 was partially supported: interpersonal and medical stress was associated higher CESD for all ethnic groups; financial stress was associated with higher CESD­­­­ for NHW and HL only.  More childhood trauma predicted higher CESD levels for all ethnic groups (ORs 1.33 to 1.38, 95% CIs 1.15 to 1.56).  Some support for H2 was found, contingent upon the type of childhood trauma experienced among NHWs and HLs; but not for AAs. For example, in NHWs, the effect of interpersonal stressors was amplified by physical abuse during childhood.  In HLs, home displacement in childhood sensitized individuals to recent medical stressors.  Conclusions: Findings suggest the depressogenic effects of stressful events in older adults vary by ethnicity and type of childhood trauma experienced.