Fear memory regulation by the cAMP signaling pathway as an index of reexperiencing symptoms in posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) is a psychiatric disorder associated with traumatic memory, yet its etiology remains unclear. Reexperiencing symptoms are specific to PTSD compared to other anxiety-related disorders. Importantly, reexperiencing can be mimicked by retrieval-related events of fear memory in animal models of traumatic memory. Recent studies revealed candidate PTSD-associated genes that were related to the cyclic adenosine monophosphate (cAMP) signaling pathway. Here, we demonstrate the tight linkage between facilitated cAMP signaling and PTSD by analyzing loss- and gain-of-cAMP signaling effects on fear memory in mice and the transcriptomes of fear memory-activated mice and female PTSD patients with reexperiencing symptoms. Pharmacological and optogenetic upregulation or downregulation of cAMP signaling transduction enhanced or impaired, respectively, the retrieval and subsequent maintenance of fear memory in mice. In line with these observations, integrative mouse and human transcriptome analysis revealed the reduced mRNA expression of phosphodiesterase 4B (PDE4B), an enzyme that degrades cAMP, in the peripheral blood of PTSD patients showing more severe reexperiencing symptoms and the mouse hippocampus after fear memory retrieval. Importantly, more severe reexperiencing symptoms and lower PDE4B mRNA levels were correlated with decreased DNA methylation of a locus within PDE4B, suggesting the involvement of methylation in the mechanism of PTSD. These findings raise the possibility that the facilitation of cAMP signaling mediating the downregulation of PDE4B expression enhances traumatic memory, thereby playing a key role in the reexperiencing symptoms of PTSD patients as a functional index of these symptoms.

Psychological distress mediates the association between COVID-19-related discrimination and subsequent PTSD symptom severity in healthcare workers: a two-year follow-up study.

BACKGROUND: Past research has suggested a cross-sectional association between COVID-19-related discrimination and PTSD symptom severity. However, no cohort study has examined the longitudinal association that better supports causal interpretation. Also, even if such an association genuinely exists, the specific pathway remains unclear. METHODS: We conducted a two-year follow-up study, obtaining data from healthcare workers in a hospital setting. We first evaluated how COVID-19-related discrimination in 2021 was associated with subsequent PTSD symptom severity in 2023. Thereafter, we conducted causal mediation analysis to examine how this association was mediated by psychological distress in 2022, accounting for exposure-mediator interaction. Missing data were handled using random forest imputation. RESULTS: A total of 660 hospital staff were included. The fully adjusted model showed greater PTSD symptom severity in individuals who experienced any COVID-19-related discrimination compared with those without such experiences (ß, 0.44; 95% CI, 0.04-0.90). Regarding each type of discrimination, perceived discrimination was associated with greater PTSD symptom severity (ß, 0.52; 95% CI, 0.08-0.96), whereas verbal discrimination did not reach statistical significance. Psychological distress mediated 28.1%-38.8% of the observed associations. CONCLUSIONS: COVID-19-related discrimination is associated with subsequent PTSD symptom severity in healthcare workers. Psychological distress may serve as an important mediator, underscoring the potential need for interventions targeting this factor.

Digital health-based exposure therapies for patients with posttraumatic stress disorder: A systematic review of randomized controlled trials.

Although exposure therapies have established effects in treating posttraumatic stress disorder (PTSD), these therapies might be hindered by issues of cost, distance, time, and human resources, which are potentially alleviated by digital health. Despite the potential of digital health, there is currently no systematic review specifically evaluating digital health-based exposure therapies. We aimed to conduct a systematic literature review of randomized controlled trials (RCTs) examining the impact of digital health-based exposure therapies in treating patients with PTSD. A literature search was conducted from December 31, 2023, to February 22, 2024, using the PubMed, Web of Science, and PsycINFO databases. A total of 12 RCTs with 1,361 participants were included in the systematic review. These RCTs were conducted mainly in the United States and primarily enrolled military samples. Overall, the utility of digital health-based exposure therapies appeared plausible and comparable to that of in-person therapies. The dropout rate was counterintuitively high, potentially due to technological issues and the absence of personal connections. The findings suggest that digital health-based exposure therapies may potentially resolve the issues of cost, distance, time, and human resources in the treatment of patients with PTSD. Future RCTs should employ larger sample sizes. Addressing technological challenges and the absence of personal connection may be important in resolving the high dropout rate.

Association of childhood maltreatment history with salivary interleukin-6 diurnal patterns and C-reactive protein in healthy adults.

Childhood maltreatment has been associated with increased inflammation, as indicated by elevated levels of proinflammatory markers such as interleukin-6 (IL-6) and C-reactive protein (CRP). Studies in humans show that secretion of IL-6 follows a clear circadian rhythm, implying that its disturbed rhythm represents an important aspect of dysregulated inflammatory system. However, possible alterations in diurnal secretion patterns of IL-6 associated with childhood maltreatment have not been studied. Here we investigated this association in 116 healthy adults. Diurnal levels of IL-6 were examined using saliva samples collected at 5 times a day across 2 consecutive days. Salivary CRP levels were also determined by averaging measurements at 2 times a day for 2 days. Different types of childhood maltreatment were assessed with the Childhood Trauma Questionnaire (CTQ). CTQ total and emotional abuse scores were significantly correlated with smaller IL-6 diurnal variation as indexed by lower standard deviation across the measurement times (p = 0.024 and p = 0.008, respectively). Individuals with emotional abuse, as defined by a cut-off score of CTQ, showed flatter IL-6 rhythm than those without (p = 0.031). These results, both correlation and group comparison, remained significant after controlling for age, sex, and body mass index. Childhood maltreatment was not associated with total output of IL-6 or CRP. Our findings indicate that childhood trauma can have a long-term negative effect on the circadian rhythm of inflammatory system. The findings are consistent with those of previous studies on adulthood trauma, suggesting that the disrupted IL-6 rhythmicity may be associated with a broad range of trauma-related conditions.

Establishing norms on the Japanese version of the Eyberg Child Behavior Inventory.

BACKGROUND: The Eyberg Child Behavior Inventory (ECBI) is one of the standardized parent rating scales used to identify disruptive behavior problems in children in Western countries. This study aimed to determine norms for the Japanese version of the ECBI, including clinical cutoff scores among the general population in Japan. METHODS: This study established norms for the Japanese version of the ECBI using a sample of 1,992 parents of children aged 2-7, living in Japan. The research evaluates the validity and the reliability of the ECBI scores for the Intensity Scale and the Problem Scale. After validation, a clinical cutoff value of the ECBI scores was calculated, setting the cutoff to above the +1 standard deviation (SD) level based on the population distribution. RESULTS: The means of the Intensity and Problem Scale scores were 100.07 and 6.57, respectively. Cronbach's α for both the Intensity and the Problem scores was 0.91. At this point, we propose cutoff scores of 125 for the Intensity Scale and 14 for the Problem Scale. CONCLUSIONS: Our results suggest that the Japanese version of the ECBI is highly reliable and may be useful as a tool for assessing behavior problems in children.

Post-disaster mental health and psychosocial support in the areas affected by the Great East Japan Earthquake: a qualitative study.

BACKGROUND: Few studies exploring the actual practices implemented for long-term mental health and psychosocial support after a natural disaster have been published. This study aimed to reveal (1) the types of activities that were actually provided as mental health and psychosocial support (MHPSS) in the long-term phase after the Great East Japan Earthquake (GEJE) and (2) the problems that must be addressed to provide post-disaster MHPSS activities. METHODS: An open-ended questionnaire was sent to organizations in the Iwate, Miyagi and Fukushima prefectures that were potentially involved in providing MHPSS to communities affected by the GEJE. The organizations were asked to describe their activities and the problems that needed to be addressed to provide these support activities. The collected statements were analysed using content analysis with NVivo11. RESULTS: The support activities conducted to provide MHPSS in the long-term phase after the catastrophe were diverse and classified into 7 major categories, namely, (1) one-on-one support for individuals in need of assistance, (2) support for collective activities, (3) support around living conditions and income, (4) increasing public awareness about mental health, (5) human resource development to improve response capabilities for MHPSS, (6) support for MHPSS providers, and (7) facilitating collaborations among the MHPSS activities provided to affected communities. Problems with human resources and funding were the most frequently mentioned concerns among the organizations participating in the survey. CONCLUSIONS: The establishment of systems to collect and share sufficient and relevant knowledge and to coordinate organizations for long-term post-disaster postventions would be desirable.

Inflammation and post-traumatic stress disorder.

While post-traumatic stress disorder (PTSD) is currently diagnosed based solely on classic psychological and behavioral symptoms, a growing body of evidence has highlighted a link between this disorder and alterations in the immune and inflammatory systems. Epidemiological studies have demonstrated that PTSD is associated with significantly increased rates of physical comorbidities in which immune dysregulation is involved, such as metabolic syndrome, atherosclerotic cardiovascular disease, and autoimmune diseases. In line with this, a number of blood biomarker studies have reported that compared to healthy controls, individuals with PTSD exhibit significantly elevated levels of proinflammatory markers, such as interleukin-1ß, interleukin-6, tumor necrosis factor-α, and C-reactive protein. Moreover, various lines of animal and human research have suggested that inflammation is not only associated with PTSD but also can play an important role in its pathogenesis and pathophysiology. In this review, we first summarize evidence suggestive of increased inflammation in PTSD. We then examine findings that suggest possible mechanisms of inflammation in this disorder in terms of two different but interrelated perspectives: putative causes of increased proinflammatory activities and potential consequences that inflammation generates. Given that there is currently a dearth of treatment options for PTSD, possibilities of new therapeutic approaches using pharmacological and non-pharmacological treatments/interventions that have anti-inflammatory effects are also discussed. Despite the increasing attention given to the inflammatory pathology of PTSD, there remains much to be elucidated, including more detailed mechanisms of inflammation, potential usefulness of inflammatory biomarkers as diagnostic and prognostic markers, and efficacy of novel treatment strategies targeting inflammation.

[Traumatic Grief and PTSD].

The concept of traumatic grief was once maintained by Prigerson in the late 1990s to be soon replaced by various concepts such as persistent grief or complicated grief, to cause a con- fusion of diagnostic criteria, the common element across those concepts being the psychological disturbance caused by the loss of a beloved one. Most contemporary psychotherapy for compli- cated grief put an emphasis upon the cognitive restructure of the meaning of the loss reflect- ing the prevailing understanding that the basis of the pathogenesis of the disorder is the loss of attachment and that the intrusion symptom is actually the yearning for the deceased. In those cases, however, where the loss of attachment is complicated by the comorbid symptoms of PTSD, caused by the death due to accident or murder, contradictory psychological processes are generated by the desire to forget the traumatic nature of the event but to maintain the vivid image of the deceased. The trauma-focused treatment is often necessary for those cases and the concept of traumatic grief, grief caused by trauma, would be clinically beneficial and should be further verified through clinical practice and research.

Serum oxytocin, posttraumatic coping and C-reactive protein in motor vehicle accident survivors by gender.

BACKGROUND: Previous studies indicate that oxytocin (OT) might play a major role in the prevention of posttraumatic stress disorder (PTSD) and that the effects of OT might differ by gender. This exploratory study aimed to clarify the relationships between the OT level and physical and psychosocial factors by gender in accident survivors. METHODS: Two hundred and thirty-five accident survivors offered blood samples at baseline, 155 of whom participated in follow-up assessments 1 month later. Spearman's correlation coefficients were calculated between the serum OT levels and physical and psychosocial factors assessed at baseline by gender. Univariate and multivariate regression analyses were then used to examine the relationships between the serum OT levels and psychological variables by gender. RESULTS: In men, the OT levels were negatively associated with C-reactive protein at baseline and did not predict any psychological variables at the 1-month follow-up. On the other hand, in women, the OT levels were positively associated with cooperativeness at baseline and predicted seeking social support, positive reappraisal, accepting responsibility and planful problem solving at the 1-month follow-up. The OT levels were not associated with PTSD, depression, and anxiety symptoms. CONCLUSIONS: The findings suggest that the role of OT in posttraumatic coping and inflammation differs by gender in accident survivors. Gender differences in the effects and mechanism of OT might be a key consideration when developing interventions using OT.

Property damage and long-term psychological distress after the 2004 Niigata-Chuetsu earthquake in Ojiya, Japan: a community-based study.

BACKGROUND: This study aimed to assess psychological distress (PD) in earthquake-stricken communities with regard to the extent of property damage for 3 years following the 2004 Niigata-Chuetsu earthquake in Japan. METHODS: Subjects were participants of health check examinations in a community near the epicentre, and included 7097 residents (≥18 years) in 2005, 6586 in 2006 and 6698 in 2007. Interviews assessed PD symptoms and lifestyles. The Kessler Psychological Distress Scale (K10) was used, with scores ≥20 considered as PD. The 137 subdistricts were divided into quartiles according to the proportion of half-completely destroyed houses at cut-offs of 18.9, 30.5 and 66.7%. RESULTS: The PD prevalence was 17.0% in 2005, 13.2% in 2006 and 11.8% in 2007. In 2005, the more and most heavily damaged groups had significantly higher PD prevalence (OR = 1.5 and 1.4, respectively) than that of the least damaged group with a dose-dependent relationship (P = 0.0005). This association was weaker in 2006 (P = 0.0413) and in 2007 (P = 0.1816). CONCLUSION: Psychological distress prevalence was high in highly damaged areas, and the prevalence difference between areas with high versus low damage decreases with time. Extensive mental health care in communities with substantial damage should be expected to last 2 years after an earthquake.

Relationships between mental health distress and work-related factors among prefectural public servants two months after the Great East Japan Earthquake.

BACKGROUND: In times of disaster, public servants face multiple burdens as they engage in a demanding and stressful disaster-response work while managing their own needs caused by the disaster. PURPOSE: We investigated the effects of work-related factors on the mental health of prefectural public servants working in the area devastated by the Great East Japan Earthquake to identify some ideas for organizational work modifications to protect their mental health. METHODS: Two months after the earthquake, Miyagi prefecture conducted a self-administered health survey of prefectural public servants and obtained 4,331 (82.8%) valid responses. We investigated relationships between mental health distress (defined as K6 ≥ 13) and work-related variables (i.e., job type, overwork, and working environment) stratified by level of earthquake damage experienced. RESULTS: The proportion of participants with mental health distress was 3.0% in the group that experienced less damage and 5.9% in the group that experienced severe damage. In the group that experienced less damage, working >100 h of overtime per month (adjusted odds ratio [OR], 2.06; 95% confidence interval [CI], 1.11-3.82) and poor workplace communication (adjusted OR, 10.96; 95% CI, 6.63-18.09) increased the risk of mental health distress. In the group that experienced severe damage, handling residents' complaints (adjusted OR, 4.79; 95% CI, 1.55-14.82) and poor workplace communication (adjusted OR, 9.14; 95% CI, 3.34-24.97) increased the risk, whereas involvement in disaster-related work (adjusted OR, 0.39; 95% CI, 0.18-0.86) decreased the risk. CONCLUSIONS: Workers who have experienced less disaster-related damage might benefit from working fewer overtime hours, and those who have experienced severe damage might benefit from avoiding contact with residents and engaging in disaster-related work. Facilitating workplace communication appeared important for both groups of workers.

Mental health distress and related factors among prefectural public servants seven months after the great East Japan Earthquake.

BACKGROUND: To develop an empirically informed support measure for workers, we examined mental health distress and its risk factors among prefectural public servants who were affected by the Great East Japan Earthquake and faced a demanding workload in the midterm of the disaster. METHODS: We conducted a self-administered health survey of all public servants in the Miyagi prefectural government two and seven months after the Great East Japan Earthquake (3743 workers, 70.6% of all employees). We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for mental distress (defined as K6 score ≥10) in the domain of disaster-work-related stressors, work-related stressors, and disaster-related stressors. RESULTS: Among those with better levels of workplace communication, the only factor that increased the risk of mental distress was not taking a non-work day each week (adjusted OR 2.55, 95% CI 1.27-5.14). Among those with poorer levels of workplace communication, in addition to not taking a non-work day each week (adjusted OR 3.93, 95% CI 3.00-5.15), handling residents' complaints (adjusted OR 1.55, 95% CI 1.00-2.42), having dead or missing family members (adjusted OR 2.87, 95% CI 1.53-5.38), and living in a shelter more than two months after the disaster (adjusted OR 2.80, 95% CI 1.32-5.95) increased the risk of mental distress. CONCLUSIONS: All workers should be encouraged to take a non-work day each week. Among workers with poor workplace communication, special attention should be given to those who handle residents' complaints, have lost a family member(s), and are living in a shelter for a prolonged period of time.

Blood mRNA expression levels of glucocorticoid receptors and FKBP5 are associated with depressive disorder and altered HPA axis.

BACKGROUND: While depression has been associated with alterations in the hypothalamic-pituitary adrenal (HPA) axis function, there is still controversy regarding the nature and extent of the dysfunction, such as in the debate about hypercortisolism vs. hypocortisolism. It may therefore be necessary to understand whether and how HPA axis function in depression is linked to mRNA expression of key genes regulating this system. METHODS: We studied 163 depressed outpatients, most of whom were chronically ill, and 181 healthy controls. Blood mRNA expression levels of NR3C1 (including GRα, GRß, and GR-P isoforms), FKBP4, and FKBP5 were measured at baseline. HPA axis feedback sensitivity was measured by the dexamethasone (Dex)/corticotropin-releasing hormone (CRH) test. The association between mRNA expression levels and HPA axis feedback sensitivity was examined. RESULTS: Compared to controls, patients showed significantly higher expression of GRα and lower expression of FKBP5, and higher post-Dex cortisol levels, even after controlling for age and sex. FKBP5 expression was significantly positively correlated with cortisol levels in patients, while GRα expression was significantly negatively correlated with cortisol levels in controls. LIMITATIONS: Most patients were taking psychotropic medications. The large number of correlation tests may have caused type I errors. CONCLUSIONS: The tripartite relationship between depression, mRNA expression of GR and FKBP5, and HPA axis function suggests that the altered gene expression affects HPA axis dysregulation and, as a result, impacts the development and/or illness course of depressive disorder. The combination of increased GRα expression and decreased FKBP5 expression may serve as a biomarker for chronic depression.

Association of COVID-19 preventive behavior and job-related stress with the sleep quality of healthcare workers one year into the COVID-19 outbreak: a Japanese cross-sectional survey.

BACKGROUND: This study aimed to evaluate the association of COVID-19 preventive behavior and job-related stress with sleep quality among healthcare workers (HCWs). We conducted a cross-sectional survey using a questionnaire at the National Center of Neurology and Psychiatry, Tokyo, Japan. METHODS: A total of 586 participants who completed the questionnaire were eligible for the study. The Pittsburgh Sleep Quality Index was used to evaluate sleep quality. We examined the level of engagement between poor sleep and COVID-19-related infection preventive behaviors, such as avoiding closed spaces, crowded places, and close contact (three Cs), a distance of at least one meter from others, wearing a face mask regularly, washing hands regularly, and working remotely, as well as job-related stress in the work environment, exposure to patients, potential risk of infection, fear of infecting others, need for social confinement, and financial instability. We conducted a hierarchical logistic regression analysis to examine the relationship between poor sleep and COVID-19 preventive behavior, job-related stress, and other covariates, including age, sex, and the Kessler Psychological Distress Scale (K6), which was used to measure non-specific psychological distress. RESULTS: Poor sleep was observed in 223 (38.1%) participants. Adherence to COVID-19 preventive measures was relatively high: 84.1% of participants answered "always" for wearing a face mask regularly and 83.4% for washing hands regularly. In the multivariate logistic regression analysis, stress in the work environment (odds ratio [OR] = 2.09, 95% confidence interval [CI], 1.37-3.20; p < 0.001), financial instability (OR = 1.73, 95% CI, 1.12-2.67; p < 0.05), and low adherence to working remotely (OR = 1.65, 95% CI, 1.06-2.57; p < 0.05) were independently and significantly associated with poor sleep after controlling for the covariates. CONCLUSIONS: One year into the COVID-19 pandemic, the poor sleep rates of HCWs remained high. These results emphasize the need to protect HCWs from work environment stress and financial concerns.

Association of sugary drinks, carbonated beverages, vegetable and fruit juices, sweetened and black coffee, and green tea with subsequent depression: A five-year cohort study.

BACKGROUND & AIMS: Evidence on the impact of beverage consumption on depression is limited in the Asian population. Specifically, there is little information available on vegetable and fruit juices, while whole vegetables and fruits are reportedly protective against depression. Furthermore, evidence is scarce in differentiating the impacts of sweetened and black coffee. We aimed to examine the association of the consumption of total sugary drinks, carbonated beverages, vegetable and fruit juices, sweetened and black coffee, and green tea with subsequent depression in a general population sample. METHODS: We studied individuals without a history of cancer, myocardial infarction, stroke, diabetes, or depression at baseline in 2011-2016, with a five-year follow-up. We used Poisson regression models and the g-formula, thereby calculating the risk difference (RD) for depression. Multiple sensitivity analyses were conducted. Missing data were handled using random forest imputation. We also examined effect heterogeneity based on sex, age, and body mass index by analyzing the relative excess risk due to interaction and the ratio of risk ratios. RESULTS: In total, 94,873 individuals were evaluated, and 80,497 completed the five-year follow-up survey for depression. Of these, 18,172 showed depression. When comparing the high consumption group with the no consumption group, the fully adjusted RD (95% CI) was 3.6% (2.8% to 4.3%) for total sugary drinks, 3.5% (2.1% to 4.7%) for carbonated beverages, 2.3% (1.3% to 3.4%) for vegetable juice, 2.4% (1.1% to 3.6%) for 100% fruit juice, and 2.6% (1.9% to 3.5%) for sweetened coffee. In contrast, the fully adjusted RD (95% CI) was -1.7% (-2.6% to -0.7%) for black coffee. The fully adjusted RD for green tea did not reach statistical significance. The results were robust in multiple sensitivity analyses. We did not find substantial effect heterogeneity based on sex, age, and body mass index. CONCLUSIONS: Total sugary drinks, carbonated beverages, vegetable and fruit juices, and sweetened coffee may increase the risk of depression, whereas black coffee may decrease it.

Longitudinal changes in serum brain-derived neurotrophic factor in accident survivors with posttraumatic stress disorder.

BACKGROUND: This prospective cohort study investigated the serum levels of brain-derived neurotrophic factor (BDNF), which mediates synaptic plasticity crucial for fear memory extinction, in patients severely injured in motor vehicle accidents (MVAs). METHOD: A nested, case-controlled study was conducted with 103 MVA survivors: 8 medication-naïve patients who met the criteria for full diagnosis of posttraumatic stress disorder (PTSD) at 6 months after MVA, 10 medication-naïve patients with partial PTSD and 85 patients with no PTSD. PTSD was evaluated by the Clinician-Administered PTSD Scale (CAPS). Serum BDNF levels were measured shortly after the MVA (baseline) and at 6-month follow-up. RESULTS: Posttrauma serum BDNF levels differed between the 3 groups after controlling for age and sex (F = 3.41, p = 0.04), with unexpectedly higher serum BDNF levels seen in the full-PTSD group compared with the no-PTSD group. Additional analysis of patients with serum samples taken at baseline and at 6 months revealed the full-PTSD group had significantly higher serum BDNF levels over the 6 months than the no-PTSD group after controlling for age and sex (F = 6.44, p < 0.01). A positive correlation was seen between changes in serum BDNF levels over 6 months and the CAPS score at 6 months (r = 0.26, p = 0.014). CONCLUSIONS: The findings of this study, the first to report longitudinal serum BDNF levels in MVA survivors, suggest that elevated serum BDNF levels could be a biomarker of PTSD after a traumatic event.

Incidence and prediction of post-traumatic stress disorder at 6 months after motor vehicle accidents in Japan.

BACKGROUND: Incidence proportion of post-traumatic stress disorder (PTSD) after motor vehicle accidents (MVA) vary considerably across countries, and whether heart rate (HR) and respiratory rate (RR) immediately after MVA predict subsequent PTSD remains controversial. This study examined the incidence proportion of PTSD at 6 months after MVA in Japan, and the predictors of PTSD in MVA survivors. METHOD: Patients with MVA-related injuries consecutively admitted to the intensive care unit of a teaching hospital in Tokyo were recruited. Six months after MVA, PTSD was diagnosed using the Clinician Administered Post-traumatic Stress Disorder Scale (CAPS). RESULTS: Of the 300 participants, 106 completed the assessments at 6 months after MVA and PTSD was diagnosed in 7.5% of the patients. Eight of the 300 participants (2.7%) were regarded as having PTSD after imputing their CAPS score at follow-up assessment for participants who dropped out. In multivariate regression analysis, no variables were shown to be independent predictors for PTSD. HR and RR did not predict PTSD in the analysis. DISCUSSION: The results suggested that the incidence proportion of PTSD following MVA in Japan was lower than that in most developed countries, and HR and RR might not be accurate screening tools despite their importance in a fear-conditioning model of the genesis of PTSD.