Many patients with workplace-related injuries present with symptoms of psychological distress, including anxiety, depression, anger, and physical and social impairments [1,2]. Especially the reported incidence of posttraumatic stress disorder (PTSD) in injured workers is higher than the rates in individuals with other types of traumatic events [2]. However, many patients with workplace-related PTSD cannot receive proper psychological management due to their physical disabilities and the limited compensation systems that allow only for short-term treatments of acute physical injuries [3]. PTSD symptoms per se are stressful experiences for patients [4], and they can also be disruptive insofar as they increase work avoidance [1,5], which, in turn, leads to a worsening of the PTSD-related symptoms. Therefore, effective treatment of PTSD following workplace injuries is necessary to achieve successful rehabilitation and comprehensive care. However, few studies have evaluated the efficacy of treatment for patients with workplace-related PTSD [6].

Although some individuals with workplace-related PTSD respond well to exposure-based therapies [1], a significant percentage of patients do not improve following only this type of treatment [7]. In addition, many of the standard treatments for PTSD, including cognitive behavioral therapy (CBT) and prolonged exposure, require a strong therapeutic alliance with the therapist [6,8] as well as a sufficient treatment period. However, individuals with physical disabilities have a difficult time participating in these treatment modalities, and the consequent drop-out rates in this population are higher than those for other groups [9]. Additionally, in most cases, patients report the absence of previous psychiatric problems and are frequently reluctant to seek psychiatric treatment due to the stigma attached to and the negative beliefs regarding mental health treatment. Therefore, the distinct characteristics of this population must be considered when developing an effective treatment program for workplace-related PTSD.

Mental imagery is a type of cognition that takes the form of perceptional experiences in the absence of direct stimuli [10] and consists of mental representations of all sensory and/or perceptual images. Because imagery has a more powerful impact on emotion than the verbal processing of the same material [11], interventions using imagery are suggested as effective tools for the relief of emotional distress, including the symptoms associated with PTSD [12]. According to the cognitive model of PTSD described by Ehlers and Clark [13], PTSD becomes persistent when traumatic information is processed in a way that leads to the sensing of a serious current threat. Therefore, one of the main therapeutic targets of this model involves updating the traumatic memory during cognitive therapy. It has been suggested that directly addressing the use of imagery can be a powerful tool for the modification of traumatic memories because cognitive-affective disturbances in trauma-related memories are embedded in the traumatic image themselves [14]. Guided imagery is a form of imagery based cognitive-behavioral techniques that produce therapeutic changes through mind-body interactions by directing individuals to create and manipulate specific mental images guided by script-based verbal instructions.

One study found that victims of industrial accidents with PTSD who failed to show improvements following prolonged exposure therapy responded to imagery based therapy [6]. Thus, the present study developed a trauma-focused and imagerybased take-home treatment program using guided imagery techniques that were based on the results achieved by variety of imagery-focused approaches. Additionally, this program borrowed techniques from various forms of mind-body training, such as breathing relaxation, muscle relaxation, and meditation, under the assumption that these tools would not only have their own therapeutic effects but would also enhance attention and concentration and enhance the effectiveness of attempts to modulate imagery [15]. Thus, the present study aimed to investigate the effectiveness of an online imagery-based program for treating the psychiatric symptoms of patients with PTSD related to workplace accidents.

Of 54 patients aged 20 to 65 years with work-related PTSD during the study period (June 2016 to September 2016), 35 were allocated to clinical trial and treated accordingly. Of the 19 subjects excluded from the study, 6 were excluded due to cognitive problems, and 13 refused to participate in the study. Four weeks later, all participants reported that they had completed at least two program listening sessions.

Table 2 presents the demographic and clinical characteristics of the study participants. Most participants were male with comorbid psychiatric symptoms, showed a chronic course of PTSD, and reported moderate levels of trauma-related guilt feelings. Additionally, 60% of the population (n=21) reported adverse childhood experiences. After 4 weeks of treatment, participants demonstrated significant improvements in terms of depression, anxiety, and PTSD symptoms (Table 3). However, there were no changes in posttraumatic growth, functional social support, or suicidality.

The subgroup analysis revealed that participants with adverse childhood experiences showed greater symptom relief, measured by scores on the GAD-7 (t=-2.142, p=0.040) and PCL (t=-3.214, p=0.003), compared to those without adverse childhood experiences (Figure 1). In terms of the PCL subscores, the groups significantly differed on avoidance (t=-2.951, p=0.006) and hyperarousal (t=-2.997, p=0.005). There were no other significant differences between the groups, including with regard to demographic and clinical characteristics.

The main purpose of the present study was to determine the therapeutic effects of an online-based treatment program for patients with work-related injuries that focused on the modulation of imagery. Although online-based methods can effectively treat psychological issues in and provide stress management for healthy participants and workers [27,28], no studies have investigated these variables in patients with workplace-related PTSD. Because the present program is based on an online platform, patients with reduced mobility can receive treatment at home. Therefore, this type of self-help intervention provides the opportunity for individuals to enhance their sense of control and mastery, which are thought to be lost in most patients with PTSD. Additionally, this treatment program is highly structured and does not require a high degree of expertise by the therapist or the inclusion of many resources, which makes this therapy affordable.

Even with a short treatment period of 4 weeks, the participants exhibited significant improvements in depression, anxiety, and PTSD symptoms. The pre-post effect size for PTSD symptoms on the PCL was reflected in a Cohen’s d value of 0.906, which is smaller than those for other CBT-based therapies for PTSD (d=1.5) [29] and similar to (d=0.85) [18] or lower than (d=1.43) [17] the rates reported for other guided imagery therapies for PTSD. These differences were likely to due to the fact that a large portion of the present sample was experiencing chronic pain. PTSD patients with chronic pain or physical injury experience higher levels of distress [30,31] and show poorer outcomes after treatment [32,33].

Overall, the dimensions that reflected responses to the present treatment program were mainly related to emotion, and these changes were attributed to the strong impact of imagery on emotional regulation [11]. In this program, imaginary exposure to the traumatic memory is not processed through habituation, as is the case with exposure-based therapy. Instead, the traumatic memory is either faded or erased via one’s imagination or substituted by pleasurable imagery. Erasing negative images can effectively decrease arousal that is associated with negative memories, whereas imagining pleasurable images can induce positive emotions. Regulating emotions with imagery-based treatments can change beliefs that the disturbing images cannot be completely controlled; at the same time, their promotion of alternatives in the form of images rather than verbal representations may render patients more likely to act on these changes [34]. These changes in the meaning of the self may allow for the development of more positive beliefs about the self.

From a clinical perspective, individuals who are exposed to childhood trauma tend to develop PTSD more often [35] and are more likely to be exposed to traumatic events in adulthood than those who did not experience childhood trauma [36,37]. However, PTSD patients with childhood trauma could be considered a distinct group based on their epigenetically-induced altered neurobiological state [38] and complex symptomatology [39], which differs from those of individuals without a history of childhood trauma. As a result, it has been suggested that PTSD patients with childhood trauma require personalized therapy. However, the effects of childhood trauma on the treatment outcomes of PTSD patients who receive CBT remain uncertain [40]. In cases of depression, existence of the childhood trauma influences treatment outcomes [41], psychotherapy is suggested to be more effective than pharmacotherapy for treating depressive patients with childhood trauma [42]. Thus, the present treatment program may be an effective treatment modality for PTSD patients with childhood trauma.

There were no significant differences in the demographic or clinical profiles of the present participants according to the presence or absence of childhood trauma. However, there are two reasons that this treatment program may be more effective in patients with childhood trauma. First, the imagery content that this treatment utilizes includes both current and childhood traumas. The manner in which childhood trauma affects psychological states in adulthood is indirectly mediated by factors such as low self-esteem and insecure attachment. However, if childhood trauma directly influences responses to a current trauma, then interventions for the childhood trauma, such as the present program, may have an effect on the reaction to the current trauma. Second, it appears that differences in imaginative suggestibility are reflected in responses to imagery-based treatments [43]. According to studies investigating the relationship between imaginative suggestibility and childhood trauma, individuals who experience trauma during childhood may develop skills related to imaginative involvement [44]. Therefore, the present results showing a greater responsiveness in the group with childhood trauma may reflect their higher degree of imaginative suggestibility.

Meanwhile, there were no significant effects of the program on posttraumatic growth, perceived social support, or suicidality. Although few studies have investigated the effects of PTSD treatment on suicidality, two reported diminished levels of suicidal ideation after evidence-based treatments [45,46]. However, the subjects in those studies consisted primarily of employed female civilians, which is quite different from the present study sample, which was composed primarily of unemployed male subjects. Improvements in PTSD symptoms are related to improvements in suicidality when depressive symptoms are accounted for [46]. Similarly, studies investigating the temporal association between suicidality and PTSD symptoms reported that the effect size for suicidality was low and that improvements in PTSD symptoms were followed by diminished suicidality [47]. Therefore, it will be necessary to confirm whether improvements in suicidality can be achieved after a sufficient period of time has passed.

In the case of posttraumatic growth as assessed using the PTGI, there were slight improvements in the dimensions assessing relating to others, new possibilities, and personal strength; however, these changes were not statistically significant. A study using the PTGI to assess the effects of PTSD treatment found significant improvements in these dimensions and showed that the pretreatment PTGI score influenced the treatment outcome [48]. The nonsignificant effect of PTGI score in the present study may have been due to the fact that the baseline PTGI scores in the present sample were approximately half the values of those in the previous study sample. Although the role that social support plays in the development of PTSD is well documented, the relationship between the course of PTSD and social support requires further investigation. Consistent with the interpersonal difficulties that accompany PTSD symptoms, some evidence indicates that perceived social support can be influenced by PTSD symptom severity [49]. However, due to the social damages experienced by PTSD patients during the long duration of their illness (an average of 5 years), a 4-week treatment period may be too brief to observe changes in the social support system of an individual [50]. Otherwise, this lack of any change could imply that there were not sufficient resources to support the patients [51].

One of weakness of the present study was that the design lacked a control group; thus, it was not possible to rule out that the therapeutic improvements resulted from a natural course or other therapeutic interventions, such medication, during the study. Additionally, this study did not collect follow-up data, which would be necessary to evaluate any additional therapeutic effects related to suicidality, posttraumatic growth, and perceived social support that were not observed in the present 4-week study period as well as to determine if the observed effects were maintained over the long term.

In conclusion, the present study showed that a short 4-week take-home imagery-based treatment program was effective for patients with workplace-related PTSD. Because PTSD is difficult to treat in its chronic stages, the application of early interventions is important from a therapeutic perspective. Therefore, due to the easy accessibility of this online program, it could be used as an effective early intervention for individuals with workplace injuries.