Deconstructing delayed posttraumatic stress disorder

According to the Diagnostic and Statistical Manual of Mental Disorders, delayed posttraumatic stress disorder (PTSD) must be diagnosed in individuals fulfilling criteria for PTSD if the onset of symptoms is at least six months after the trauma. The purpose of this thesis was to establish the prevalence of delayed PTSD and to examine factors that may explain its occurrence. We conducted a meta-analysis and examined prospective data from disaster survivors, unaccompanied refugee minors, and armed forces deployed to Afghanistan. Delayed PTSD occurred in about one quarter of all PTSD cases. The risk of delayed PTSD did not decrease between 9 and 25 months after the traumatic event, and when traumatized populations were followed up for longer periods of time, more delayed PTSD cases were found. These findings suggest ongoing potential risk to some individuals. Delayed PTSD occurred most often in individuals already reporting subthreshold symptoms. Prodromal symptoms included intrusive memories and avoidance of reminders as well as feelings of depression and anxiety. We found a high likelihood of mental health services utilization in participants endorsing delayed PTSD 4 years after a disaster. Two thirds of disaster survivors endorsing delayed PTSD used or continued using mental health services. This finding strongly suggests that symptom progression in delayed PTSD is clinically relevant. We found the severity of traumatic event exposure to be related to PTSD progression after a disaster in individuals reporting total home destruction and after military deployment. We also found that cognitive ability as indicated by higher education was associated with PTSD progression after a disaster, presumably by mitigating initial distress. Lack of perceived social support as well as new stressful life events increased the risk of delayed PTSD after a disaster. In unaccompanied refugee minors, increasing age emerged as a risk marker for delayed PTSD. This highlights the importance of the stressful transitions for these youths at the age of 18 years. They will be moved to more independent living arrangements if they had previously lived in living arrangements with more supervision. Furthermore, their legal status will be reviewed and they will be aware of uncertainty regarding their future right to remain in the Netherlands. Thus, factors associated with delayed PTSD may explain its occurrence in one of three ways. First, factors may increase the risk for PTSD in general. Second, factors may promote initial adaptation to the traumatic event and thus explain why symptoms are not full-blown from the start. Third, factors may precipitate PTSD onset despite initial adaptation and thus explain why symptoms increase in number or severity later on. We found prospective evidence of stress sensitization, i.e. enhanced reactivity of individuals to new stressors following exposure to severe traumatic stressors. Stress sensitization may explain progression of distress over time and has important practical implications. Averting foreseeable stressors and resource losses in the aftermath of severe trauma, diminishing the impact of chronic stressors as well as reducing stress sensitization may be a target for preventing and treating progression of posttraumatic distress