Treating intrusive memories after trauma in healthcare workers: a Bayesian adaptive randomised trial developing an imagery-competing task intervention

Abstract

Intensive care unit (ICU) staff continue to face recurrent work-related traumatic events throughout the COVID-19 pandemic. Intrusive memories (IMs) of such traumatic events comprise sensory image-based memories. Harnessing research on preventing IMs with a novel behavioural intervention on the day of trauma, here we take critical next steps in developing this approach as a treatment for ICU staff who are already experiencing IMs days, weeks, or months post-trauma. To address the urgent need to develop novel mental health interventions, we used Bayesian statistical approaches to optimise a brief imagery-competing task intervention to reduce the number of IMs. We evaluated a digitised version of the intervention for remote, scalable delivery. We conducted a two-arm, parallel-group, randomised, adaptive Bayesian optimisation trial. Eligible participants worked clinically in a UK NHS ICU during the pandemic, experienced at least one work-related traumatic event, and at least three IMs in the week prior to recruitment. Participants were randomised to receive immediate or delayed (after four weeks) access to the intervention. Primary outcome was the number of IMs of trauma during week 4, controlling for baseline week. Analyses were conducted on an intention-to-treat basis as a between-group comparison. Prior to final analysis, sequential Bayesian analyses were conducted (n=20,23,29,37,41,45) to inform early stopping of the trial prior to the planned maximum recruitment (n=150). Final analysis (n=75) showed strong evidence for a positive treatment effect (Bayes factor, BF=1.25 × 106): the immediate arm reported fewer IMs (median=1, IQR=0-3) than the delayed arm (median=10, IQR=6-16.5). With further digital enhancements, the intervention (n=28) also showed a positive treatment effect (BF=7.31). Sequential Bayesian analyses provided evidence for reducing IMs of work-related trauma for healthcare workers. This methodology also allowed us to rule out negative effects early, reduced the planned maximum sample size, and allowed evaluation of enhancements. Trial Registration NCT02044809 (www.clinicaltrials.gov).

Temporal dynamics of trauma memory persistence

“…The number of times a memory intrudes can be counted and recorded (say, in a diary). A reduction in the probability of the number of intrusions over a given time period is a primary outcome measure for recent intervention development [30–32]. Our stochastic framework can be used to simulate different treatment interventions.…”

“…Laboratory and clinical studies have shown that treatment interventions with a cognitive task can reduce the propensity of the intrusive memories to (re)consolidate following a memory reminder cue soon after a trauma [28–31,45]. Furthermore, there is emerging evidence for the success of these interventions when delivered at later time intervals since the trauma occurred [32,46,47]. Here, we have shown that delivering multiple doses or different (task) interventions is likely to achieve greater marginal gains in reducing the probability of intrusive memories reconsolidating than simply increasing the strength of a single-task intervention.…”

Memory persistence: from fundamental mechanisms to translational opportunities

“…After treatment, the event becomes available to declarative memory without evoking the strong pathological emotion characteristic of PTSD. Also, within the behavioural interventions, playing Tetris after a memory reminder cue reduced traumatic memory intrusions in traumaexposed patients [98] and intensive care unit staff [99], two subpopulations with increased vulnerability to disease onset [100].…”

Temporal dynamics of trauma memory persistence

“…The number of times a memory intrudes can be counted and recorded (say, in a diary). A reduction in the probability of the number of intrusions over a given time period is a primary outcome measure for recent intervention development [30,31,32]. Our stochastic framework can be used to simulate different treatment interventions.…”

“…Laboratory and clinical studies have shown that treatment interventions with a cognitive task can reduce the propensity of the intrusive memories to (re)consolidate following a memory reminder cue soon after a trauma [29,30,31,45]. Furthermore, there is emerging evidence for the success of these intervention when delivered a later time intervals since the trauma occurred [32,46,47]. Here, we have shown that delivering multiple doses or different (task) interventions is likely to achieve greater marginal gains in reducing the probability of intrusive memories reconsolidating than simply increasing the strength of a single task intervention.…”