Abstract
Intrusive memories are a hallmark symptom of post-traumatic stress disorder (PTSD) and oxytocin has been implicated in the formation of intrusive memories. This study investigates how oxytocin influences the acquisition and consolidation of trauma-associated memories and whether these effects are influenced by individual neurobiological and genetic differences. In this randomized, double-blind, placebo-controlled study, 220 healthy women received either a single dose of intranasal 24IU oxytocin or a placebo before exposure to a trauma film paradigm that solicits intrusive memories. We used a “general random forest” machine learning approach to examine whether differences in the noradrenergic and hypothalamic-pituitary-adrenal axis activity, polygenic risk for psychiatric disorders, and genetic polymorphism of the oxytocin receptor influence the effect of oxytocin on the acquisition and consolidation of intrusive memories. Oxytocin induced significantly more intrusive memories than placebo did (t(188.33) = 2.12, p = 0.035, Cohen’s d = 0.30, 95% CI 0.16–0.44). As hypothesized, we found that the effect of oxytocin on intrusive memories was influenced by biological covariates, such as salivary cortisol, heart rate variability, and PTSD polygenic risk scores. The five factors that were most relevant to the oxytocin effect on intrusive memories were included in a Poisson regression, which showed that, besides oxytocin administration, higher polygenic loadings for PTSD and major depressive disorder were directly associated with a higher number of reported intrusions after exposure to the trauma film stressor. These results suggest that intranasal oxytocin amplifies the acquisition and consolidation of intrusive memories and that this effect is modulated by neurobiological and genetic factors. Trial registration: NCT03031405.
Highlights
A leading symptom of post-traumatic stress disorder (PTSD) is the intrusive re-experience of a traumatic event [1]
Biomarkers associated with psychosocial stress, such as cortisol, salivary α-amylase, and heart rate variability (HRV), have been associated with intrusive memories after trauma [12,13,14,15]
There was a significant change in cortisol levels (F(2.06, 410.16) = 9.04, p ≤ 0.001), salivary α-amylase (sAA) activity (F (4.423, 880.19) = 13.59, p ≤ 0.001), and HRV (F(4.63, 795.95) =
Summary
A leading symptom of post-traumatic stress disorder (PTSD) is the intrusive re-experience of a traumatic event [1]. Intrusive memories are defined by recurrent involuntary distressing recollections or nightmares of the experienced trauma [2]. While intrusive memories after traumatic events are part of a normal adaption process [3], their frequency [4, 5], vividness, and perceived distress are predictive of PTSD [6,7,8,9]. Biological factors that influence the development of these intrusive memories are not sufficiently understood. Biomarkers associated with psychosocial stress, such as cortisol, salivary α-amylase (sAA), and heart rate variability (HRV), have been associated with intrusive memories after trauma [12,13,14,15]
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