Incidence of PTSD in the French population a month after the COVID-19 pandemic-related lockdown: evidence from a national longitudinal survey

The Coronavirus disease-2019 (COVID-19) emerged in late 2019 in China and spread rapidly in early 2020, and continued to circulate actively for the next 2 years, affecting million people worldwide with more than 535 million confirmed cases and leading to 6 million deaths by June 2022 [1]. With France among the European countries most strongly affected by this disease in 2020, French health authorities, like those of many countries, decided in March 2020 to implement a generalized nationwide lockdown. It started on March 17 and ended on May 10. Experts warned early on about the risks of increased psychological disorders, including posttraumatic stress disorders (PTSD) [2, 3]. Previous studies from China showed that PTSD was one of the most prevalent long-term psychiatric disorders among severe acute respiratory syndrome (SARS) survivors [4]. In view of the unprecedented magnitude of the COVID-19 pandemic, even as early as April, authors recommended investigation of PTSD symptoms in the general population and among health professionals [3]. Since, literature has tended to confirm experts’ fears, with variations by country, epidemic intensity and specific population groups [5‐13]. A month after the lockdown began, PTSD prevalence was 2.7% among home-isolated Chinese university students [6] and 6.1% among the Chinese population aged 17-63, with youth, women, and people with responsibilities and concern for others more vulnerable to these symptoms [8]. PTSD estimates in Europe include 28% among adult Italian COVID-19 survivors 1 month after hospital discharge [9], 27.5% in the Italian general population during the first month of lockdown [10], and 15.8% in the Spanish general population during the equivalent period there [11]. In France, the prevalence of probable PTSD was found around 19.5% among university students 1 month after the COVID-19 lockdown [12], and 21.2% among hospital workers at least 3 months after the lockdown [13]. To our knowledge, no studies have been published yet on the PTSD incidence in the French general population in relation to COVID-19, although recent studies have shown an increase in the prevalence of COVID-19-associated psychological disorders (anxiety and depression) and sleep difficulties [14, 15].

To expand our knowledge of COVID-19’s consequences on mental health in France, we conducted the COCONEL cohort survey to 1) quantify the incidence of PTSD in the general population, 2) characterize the relative frequency of the PTSD symptoms observed, 3) study the sociodemographic, economic, and COVID-19-related factors, including media use to obtain information about the pandemic, associated with PTSD onset, and 4) study PTSD’s comorbidity with generalized anxiety and depression.

This study aimed to investigate the incidence of PTSD in the French population 1 month after the end of the lockdown period. Six respondents in ten reported traumatic experiences during this period, and most of them reported several types of events. Among those with at least one traumatic event, 30.1% had PTSD 1 month after the lockdown ended, while the incidence was 17.5% (95% CI = 15.7–19.3) in the general population. The risk of PTSD in the general population was higher in people with high COVID-19-related media use, with at least mild anxiety during the lockdown, and diagnosed with COVID-19. PTSD was also strongly comorbid with anxiety, depression, and sleep problems at follow-up. Among people reporting a traumatic event, young age and exposure to multiple types of traumatic events were associated with increased PTSD risk.

Several studies have measured PTSD incidence during this pandemic, with various instruments and definitions. Some measured acute stress, e.g., at the epidemic peak [5‐8, 11, 22]. Others measured PTSD in specific groups: people aged 18-30 [22], or hospitalized for COVID-19 [9], or healthcare workers [7, 13]. Some of these samples showed marked selection [6, 9, 12, 13]. These methodological variations make comparisons between studies difficult, especially given the different cultural contexts. These studies report PTSD incidence after the lockdown ranging from 4.6 to 31.8%. Our definition of PTSD followed the American Psychiatric Association (APA) guidelines rather than using the more common global score approach. This choice should have improved our screening, because we used each PTSD symptom cluster to identify PTSD, taking their different specificity values into account [23].

Most recent review study have highlighted that health professional was concerned but also COVID-19 patients and general population [24]. Studies have found higher PTSD risks in women than men [6‐12]; this gender imbalance has also been observed for the lockdown’s impact on anxiety, depression, and sleep problems [14, 15]. This association did not appear in this study of PTSD incidence, most likely because our inclusion of anxiety and depressive disorders in our multivariate analyses captured at least part of the gender effect (Table 3). Our finding that young people exposed to traumatic events during the lockdown are at higher risks of PTSD is consistent with previous findings [10, 22, 23]. Young people, especially those with precarious jobs, may suffer more than other population segments from the pandemic’s direct economic consequences, as during earlier health crises [24, 25]. The health risks might have compromised their education, and possibly their entry into the labor market. They may also be more highly exposed to stressful information than the rest of the general population [26] and more vulnerable to aspects of the lockdown, including isolation, social distancing, the closing of places young people gather to socialize, and reduced outdoor activities. All these factors could have made them more vulnerable to traumatic events.

As in recent studies [5, 9, 12, 15, 25], PTSD risk was higher in participants with direct exposure to COVID-19, especially in those diagnosed with it, and remarkably in people indirectly exposed via high media use. Conversely, low media exposure was associated with a low PTSD risk. This result adds to previous observations of a positive relation between media exposure to information about this illness and psychological distress, anxiety, and depression [15, 26]. Ahern et al. [27] observed a similar relation between PTSD occurrence and media use after the World Trade Center attacks of September 11, 2001, although the nature and intensity of the trauma (e.g., viewing defenestration) differed greatly from what the media showed during the COVID-19 health crisis (e.g., patients in intensive care and daily recitals of the number of new and total deaths). Our findings support the recommendation by Olagoke et al. [26] that public health professionals should work with the media to provide more content about mental health resources in pandemic situations, especially during lockdowns when people are more highly exposed to media coverage than usual. Moreover, our results suggest that probable GAD during the lockdown was predictive of PTSD a month later; evidence indicating that individuals with a history of psychological disorders are at higher risk of PTSD is now supported by several post-COVID-lockdown studies [10, 11]. The media could participate in prevention programs to encourage people with anxiety symptoms during a lockdown to seek care. Trained health professionals could thus provide individual PTSD prevention care.

The collection of data in two waves a month apart allowed us to explore the persistence of the perception of stress related to traumatic events. While acute stress was perceived more frequently than persistent stress, the latter was more highly correlated to incident PTSD, although no longer significantly after comorbidity factors were included in the model. PTSD–depression comorbidity has frequently been noted in the literature, among military personnel (exposed to combat), victims of sexual assault [30], and even students during the COVID-19 epidemic [6]. Previous population-based studies have also highlighted PTSD–anxiety comorbidity [28]. Similarly, our results about sleep disorders are consistent with earlier findings of serious sleep problems in PTSD patients [10, 29], including in a recent Chinese study during its lockdown [8]. As with comorbid depression, the causal relation between sleep disorders and PTSD is complex and partly reciprocal. Although nightmares of the traumatic event are included in the DSM-5 diagnostic criteria for PTSD, sleep disorders may be both a risk factor and an outcome of PTSD [10, 30]. Doctors should be aware that people with anxiety and/or depression symptoms and/or sleep problems, even some time after lockdown, may also suffer from PTSD and should thus routinely screen for it. Clinicians could systematically use tools -e.g. the Short PTSD Rating Interview (SPRINT)- to investigate PTSD in people with these symptoms. Moreover, the strong association we observed between PTSD and suicidal thoughts underlines the potential suicidal risk in patients with PTSD. Previous findings have shown that this risk is non-negligible in people with PTSD [20], especially those with psychiatric comorbidity. Assessing the suicide risk in caring for patients with PTSD after COVID-19 lockdowns is essential.

More generally, our findings raise the question of the nature of traumatic events in a pandemic containment context. Risk was highest for those reporting several sources of traumatic events. Government announcements alone were not associated with PTSD risk in the multivariate analysis, but were rather mostly cited by people exposed to several types of events during the lockdown. Therefore, in addition to other stressful events, these announcements may have played a role in augmenting the risk. The DSM-5 definition of trauma, however, requires “actual or threatened death, serious injury, or sexual violence”: proximity to death and/or physical violence was infrequent in the traumatic events reported in our study and is reflected in the low prevalence of intrusion symptoms in our results (Additional file 1: Table 1). Nonetheless, the DSM-5 definition has been controversial [31, 32], with several studies reporting that events classically considered nontraumatic (such as losing one’s job) are nevertheless associated with higher rates of PTSD than events considered traumatic [32]. Our findings suggest that the combination of several perceived traumatic events — even if they rarely involved proximity to death or violence — could expose people at high risk to PTSD in situations such as a pandemic-related lockdown. North et al. [23] suggested a new PTSD-like syndrome, resulting from a “nontraumatic” stressor, could be named “post-stressor stress disorder”. This expression might be applied to our findings as we await further studies to clarify the traumatic nature of each reported event during COVID-19-related lockdowns. Nevertheless, the daily presentation of the death toll in the media might suffice to meet the criterion of proximity to death required by DSM-5, and forced isolation, deprivation of liberty, the loss of a job and income could be viewed as social violence. Further research, particularly clinical, is needed to confirm these hypotheses and to explore in more detail the nature of the trauma experienced by people with PTSD a month after the COVID-19-related nationwide lockdown. Follow-up of these people for months will be key.

This study has some limitations. First, because the lockdown obviously affected data collection activities, online surveys were used to administer questionnaires. While effective, online surveys may involve some bias, in view of the risk that segments of the general population might be missed. The risk is nonetheless limited, given that 89% of French households have internet access, according to a 2018 estimate [33]. Moreover, the invitation email did not mention the study topic, which may have limited potential selection bias due to non-observed factors. While the PCL-5 used to define PTSD is a well-established and often used instrument, it is not a diagnostic instrument; the lack of clinical assessment is a limit of our population-based study. Psychiatric examinations are necessary in patients whose PTSD has been detected by the PCL-5. This should be organized in cohort studies to follow patients for sufficient time to study the course of PTSD, detect cases occurring sometime after the lockdown, and evaluate the impact of the second wave of COVID-19.

In conclusion, this study is the first to document with a longitudinal design the incidence of PTSD in the French population, a month after the first COVID-19 lockdown ended. It contributes to the demonstration of the psychological impact of the pandemic in the French population and suggests the need for more psychological support and a nationwide mental health promotion program in the general population and in specific groups. PTSD prevention and treatment should focus especially on young people with a history of anxiety, those who spend substantial time following COVID-19 in the media, and those with comorbidities. Recommendations should be developed for GPs about the detection of PTSD and how to deal with probable cases.