Purpose: Guided by the hypothesis that early adversity can heighten the stress response, creating an enhanced vulnerability depression throughout the lifespan, this analysis investigates the transient versus enduring associations of different types of trauma with risk for depression over time.

Methods: Rates of DSM-IV-defined lifetime depression, age at onset of depression, and rates of endorsement of ten traumatic events were derived from a diagnostic interview of twins enrolled in an Australian twin register. Variables were constructed for each traumatic event which indicated whether an individual's first depressive episode occurred (1) before the reported event, (2) within one year after the event, (3) within 5 years after the event, (4) within 10 years, (5) within 15 years after the event. These trauma variables were used as lagged covariates for testing the length of time for which the association between reported trauma and risk for depression remained significant. Cox regression was used to test associations of the traumatic events with risk for depression over time, taking into account the age at onset of depression.

Results: Childhood neglect and childhood sexual and physical abuse had the most enduring associations with risk for depression over time. Each had an association with risk for depression that remained for ten years after the first reported experience of the event. Furthermore, a larger percentage of individuals who endorsed these events went on to have a first episode of depression even fifteen years after their first reported experience of these events, compared to the other events queried (accident, disaster, witnessing injury or killing, adult rape and sexual molestation, severe physical assault, and being threatened with a weapon or kidnapped). Childhood neglect and sexual and physical abuse were also strong predictors of first onset of depression at age 18 or younger, versus adult onset depression. The remaining events, by contrast, either had no enduring association with risk, or had associations that were only during the year following the reported event.

Implications: This analysis contributes to a growing body of evidence that early trauma does increase risk for depression even more than a decade after its occurrence, strengthening arguments for the design and funding of programs targeted at reducing the incidence of early abuse.