Do childhood adversity and being female add up, or multiply, for mental illness?
Women who experienced several childhood adversities had rates of depression and anxiety disorders well above what you would expect by simply adding the separate risks of being female and of childhood adversity.
Source
The interaction of adverse childhood experiences and gender as risk factors for depression and anxiety disorders in US adults: a cross-sectional study
Study at a glance
- Design
- Cross-sectional — Pooled cross-sectional analysis of two MIDUS national cohorts; covariate-adjusted prevalences for 8 gender-by-ACE groups and additive interaction contrasts.
- N
- N=4344 · 4344 of 5834 MIDUS participants who returned the self-administered questionnaire with complete ACE items.
- Population
- Non-institutionalised English-speaking US adults aged 25 to 84 recruited by random-digit dialling (MIDUS 2 and MIDUS Refresher).
- Outcome
- 12-month prevalence of a major depressive episode and of an anxiety disorder (panic disorder and/or generalised anxiety disorder), assessed with the CIDI-SF.
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
The authors pooled survey data from two nationally representative samples of US adults. Participants recalled five kinds of adverse childhood experiences (emotional, physical and sexual abuse, household substance abuse, and parental divorce), and a phone interview assessed depression and anxiety disorders over the past year. They estimated adjusted prevalences for every combination of gender and adversity level and tested whether the combined group exceeded the sum of the separate effects (additive interaction), as well as the usual multiplicative interaction.
What they found
Women had about twice the odds of major depression (odds ratio 2.24) and anxiety disorders (2.40) compared with men, and odds rose with the number of adversities. Among women with 3 to 5 adversities, adjusted depression prevalence was 26.9%, which was 10.2 percentage points higher than the additive expectation; anxiety prevalence was 21.9% against an expected 10.5%. These synergy effects were significant on the additive scale but not the multiplicative (logistic) scale, which may explain why earlier studies reported no interaction.
The limits
What it doesn't show
Because it is a single cross-sectional survey, it cannot establish causation, and childhood adversity was recalled in adulthood, so recall bias and misclassification are possible. Only five of the usual ten ACE categories were available, diagnoses came from a brief structured interview rather than a clinical assessment, and sex and gender identity were not measured separately. The paper interprets the synergy as possibly reflecting sexism, but no data on sexism were collected, so that mechanism is untested.
Key terms
- Adverse childhood experiences (ACEs)
- Potentially traumatic events before age 18, such as abuse or household dysfunction, usually counted into a cumulative score.
- Additive interaction (synergy)
- When the risk with both factors together is greater than the sum of the risks from each factor alone.
- Multiplicative interaction
- When the combined effect differs from the product of the separate relative effects; this is what an interaction term in a logistic regression tests.
- Interaction contrast
- Observed prevalence with both risk factors minus the prevalence expected from adding their separate effects; a value above zero indicates synergy.
- Recall bias
- Systematic error that arises when people's memories of past exposures are inaccurate or influenced by their current state.
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Quiz yourself
What does 'additive interaction' mean in this study?
Common questions
Why does it matter whether interaction is tested on the additive or multiplicative scale?
The two scales can disagree. Here the combined effect was not bigger than the product of odds ratios, but it was bigger than the sum of risk differences. For public health, the additive scale shows how many extra cases arise when both factors are present, which is what matters for targeting prevention.
Were women more likely than men to report childhood adversity?
Not overall: the proportion reporting at least one ACE was similar for men and women. Women more often reported sexual abuse and men more often reported physical abuse, but the synergy reflects how strongly adversity relates to disorder, not how often it occurs.
Does this study prove that sexism causes depression?
No. Sexism was not measured. The authors propose it as one plausible reason for the synergy, but the data only show the statistical pattern.
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