A minority of earthquake-exposed individuals develop post-traumatic stress disorder (PTSD), often alongside comorbid depression and anxiety symptoms. No systematic review has examined psychological interventions for adults with substantial earthquake-related PTSD symptoms.

To synthesise studies evaluating psychological interventions for adult earthquake-related PTSD and conduct meta-analyses estimating overall effect sizes.

The review was pre-registered with PROSPERO (CRD42023441020). PsycINFO, MEDLINE, EMBASE, CINAHL and Scopus were searched for studies (last search conducted July 2024). Randomised controlled trials (RCTs), non-randomised and non-controlled studies evaluating psychological interventions for adults with substantial earthquake-related PTSD symptoms were eligible. Outcomes were PTSD, depression and anxiety symptoms. Narrative syntheses and meta-analyses summarised study findings. The Mixed Methods Appraisal Tool guided quality assessments.

Sixteen studies were identified (eight RCTs, four non-randomised and four non-controlled studies), representing 1315 participants receiving psychological intervention. Interventions included cognitive behavioural therapy (CBT), specific CBT variants, eye movement desensitisation and reprocessing, interpersonal psychotherapy and an internet-based intervention focusing on social cognitive theory. Studies generally reported statistically and clinically significant improvements associated with psychological interventions. Among studies included in meta-analyses, overall effect size was 2.11 (95% CI = 0.92, 3.31) for PTSD symptoms and 1.01 (95% CI = 0.50, 1.52) for depression symptoms.

Psychological interventions are associated with good outcomes among adults with earthquake-related PTSD. The most evidence currently exists for CBT-based interventions, which are recommended as first-line treatments. Efficient intervention options, including single-session and group-based treatments, also show promise and are recommended for addressing widespread treatment need.

History of prior mental disorder, particularly post-traumatic stress disorder (PTSD), increases risk for PTSD following subsequent trauma exposure. However, limited research has examined differences associated with specific prior mental disorders among people with PTSD.

The current study examined whether different prior mental disorders were associated with meaningful differences among individuals presenting to a specialist service for severe earthquake-related distress following the Canterbury earthquakes (N = 177).

Two sets of comparisons were made: between participants with no history of prior disorder and participants with history of any prior disorder; and between participants with history of prior PTSD and those with history of other prior disorders. Comparisons were made in relation to sociodemographic factors, earthquake exposure, peri-traumatic distress, life events and current psychological functioning.

Participants with any prior mental disorder had more current disorders than those with no prior disorder. Among participants with history of any prior disorder, those with prior PTSD reported more life events in the past 5 years than those with other prior disorders.

Findings suggest a history of any prior mental disorder contributes to increased clinical complexity, but not increased PTSD severity, among people with PTSD seeking treatment. Although post-disaster screening efforts should include those with prior mental disorders, it should also be recognised that those with no prior disorders are also at risk of developing equally severe PTSD.