Exogenous corticosteroid exposures are associated with increased recollection of traumatic life events

Exogenous corticosteroid exposures are associated with depression in clinical samples, however, the mechanisms underlying this association are unknown. Recent animal studies have shown that corticosteroids enhance conditioning in stressful learning paradigms. It has been hypothesized that corticosteroids may enhance the recollection of stressful experiences in humans, potentially contributing to the etiology of corticosteroid induced depression. This hypothesis has not been evaluated in human subjects.

The first phase of the Canadian National Population Health Survey collected data from a probability sample of 17626 members of the general Canadian population over the age of 12. The data set included measures of drug exposure (including corticosteroid exposures) and childhood and adult psychosocial stressors, including traumatic life events. In this study, self-reported traumatic life events were cross-tabulated against corticosteroid exposures in order to evaluate whether these variables were associated.

52% of subjects treated with corticosteroids in the month prior to the interview, as compared to 41% of non-exposed subjects reported one or more of the following stressors: parental divorce, long term parental unemployment, a "frightening" event that was "thought about for years after", being sent away from home for doing something wrong, parental drug or alcohol abuse, or physical abuse. This difference was statistically significant at the 5% level of confidence.

The use of cross-sectional survey data in this study precluded confirmation that changes in the pattern of trauma recollection followed exposure to corticosteroids. Also, the study relied on unconfirmed self reported medication exposure data, and ratings from brief survey instruments concerned with life events, stress levels and traumatic experiences.

What we report is consistent with, but not confirmatory of, the hypothesis that increased recollection of stressful events may be a mechanism underlying associations between corticosteroids and depression. Additional research is needed in order to determine whether the basis for this association is an altered recollection of life events, or in a differing pattern of life experiences.