Association of Trauma, Post Traumatic Stress Disorder and Non-Affective Psychosis across the life course: A Nationwide Prospective Cohort Study

Judith Allardyce, Anna-Clara Hollander, Syed Rahman, Christina Dalman, Stan Zammit

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Background
We aimed to examine the temporal relationships between traumatic events (TE), Post traumatic Stress Disorder (PTSD) and non-affective psychotic disorders (NAPD).

Methods
A prospective cohort study of 1,965,214 individuals born in Sweden between 1971-1990 examining the independent effects of interpersonal and non-interpersonal TEs on incidence of PTSD and NAPD using data from linked register data (Psychiatry-Sweden). Mediation analyses tested the hypothesis that PTSD lies on a causal pathway between interpersonal trauma and NAPD.

Results
Increasing doses of non-interpersonal and interpersonal TEs were independently associated with increased risk of NAPD (Linear-trend IRRadjusted =2.17 (95% C.I. 2.02, 2.33) and IRRadjusted = 1.27 (95% C.I. 1.23, 1.31), respectively). There was a 5% attenuation in IRRs for non-interpersonal TEs and 10% for interpersonal TEs in 5yr-lagged models with covariates. A similar pattern of results was observed for PTSD (Linear-trend IRRadjusted = 3.43 (95% C.I. 3.21, 3,66 and IRRadjusted = 1.45, 1.39, 1.50). PTSD diagnoses increased risk of NAPD (IRRadjusted = 8.06; 95%CI 7.23, 8.99), which was substantially attenuated, in 5year-lagged analyses (IRRadjusted = 4.62; 95%CI 3.65, 5.87). There was little evidence that the diagnosis of PTSD mediated the relationship between interpersonal-TE and NAPD (IRRadjusted = 0.92; percentile CI 0.80, 1.07).

Conclusion
The strong association between trauma, PTSD and NAPD observed in this study suggests trauma is a likely component cause in the onset of psychotic disorders. This relationship is likely to be complex and PTSD diagnosis is unlikely to be the best proxy for the complex psychological mechanisms underpinning this association.
Original languageEnglish
JournalPsychological Medicine
Publication statusAccepted/In press - 21 Jul 2021

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