Repository logo

Reducing intrusive memories after trauma via an imagery-competing task intervention in COVID-19 intensive care staff: a randomised controlled trial.

Published version

Repository DOI

Change log


Iyadurai, Lalitha 
Highfield, Julie 
Markham, Alfred 


Intrusive memories (IMs) after traumatic events can be distressing and disrupt mental health and functioning. We evaluated the impact of a brief remotely-delivered digital imagery-competing task intervention on the number of IMs for intensive care unit (ICU) staff who faced repeated trauma exposure during the COVID-19 pandemic using a two-arm, parallel-group, single-blind randomised controlled trial, with the comparator arm receiving delayed access to active treatment (crossover). Eligible participants worked clinically in a UK NHS ICU during the pandemic and had at least 3 IMs of work-related traumatic events in the week before recruitment. Participants were randomly assigned (1:1) to immediate (weeks 1-4) or delayed (weeks 5-8) intervention access. Sequential Bayesian analyses to optimise the intervention and increase trial efficiency are reported elsewhere [1]. The primary endpoint for the pre-specified frequentist analysis of the final study population compared the number of IMs experienced in week 4 between the immediate and delayed access arms. Secondary outcomes included clinical symptoms, work functioning and wellbeing. Safety was assessed throughout the trial by scheduled questions and free report. All analyses were undertaken on an intention-to-treat basis (86 randomised participants). There were significantly fewer intrusive memories during week 4 in the immediate (median = 1, IQR = 0-3, n = 43), compared to the comparator delayed arm (median = 10, IQR = 6-17, n = 43), IRR 0.31, 95% CI: 0.20-0.48, p < 0.001. After crossover, the delayed arm also showed a significant reduction in IMs at week 8 compared to week 4. There were convergent findings for symptoms of PTSD, insomnia and anxiety, work engagement and burnout, general functioning and quality of life. The intervention was found safe and acceptable to participants. All adverse events were unrelated to the study. Our study provides the first evidence of a benefit on reducing IMs, improving other clinical symptoms, work functioning and wellbeing, as well as safety of a brief remotely-delivered digital imagery-competing task intervention. An efficacy trial with an active control and longer follow-up is warranted. The trial is registered at (NCT04992390).


Acknowledgements: This work was supported by the Wellcome Trust (223016/Z/21/Z). For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission. Tetris® has been licenced for use within i-spero® from The Tetris Company at no cost. The authors would like to thank the Intensive Care Society, in particular Dr Sandy Mather and Alex Day; our Data Monitoring Committee members including Prof Andreas Reif, Prof Steve Hollon, and Prof Ian Penton-Voak; our Trial Steering Committee including Pooyan Behbahani and Rebecca Dias; Expert Advisors including Dr Nick Grey, Prof Sir Simon Wessely, and Prof Jonathon Bisson; members of the study team including Veronika Kubičková, Katie Hurman and Zunaid Islam; our IT Team and Data Management Team at P1vital Products Ltd; Paul Guest (Otto-von-Guericke-University, Magdeburg, Germany and University of Campinas, São Paulo, Brazil) for useful discussion, editing and development of the final draft; statistical discussion with Philip Millroth.


Humans, Bayes Theorem, Pandemics, Quality of Life, Single-Blind Method, COVID-19, Critical Care

Journal Title

Transl Psychiatry

Conference Name

Journal ISSN


Volume Title



Springer Science and Business Media LLC
Medical Research Council (MC_UU_00002/14)