by Michael D. Anestis, M.S.
Happy New Year, everyone! I am excited to begin another year of PBB and hope that this year's articles provide you with useful, clear, and at times entertaining information about mental illness and psychotherapy. Remember, our goal here is to be a place that readers can come to learn about the science that goes into our understanding of clinical psychology, even if they have no access to or experience with reading about scientific studies. That being said, we always welcome your thoughts and comments when one of our articles seems unclear or you still have questions on a particular topic.
Today, I would like to talk about an interesting study I came across in the most recent issue of the Journal of Abnormal Psychology. In this study, Bernice Andrews, Chris Brewin, Lorna Stewart, Rosanna Philpott, and Jennie Hejdenberg (2009) worked with a sample of war veterans from the British military in order to determine if there are meaningful differences between those who experience significant trauma during deployment and develop PTSD immediately and those who either develop PTSD much later or never develop it at all. In order for an individual to meet criteria for PTSD, the DSM-IV-TR requires that a month pass after the traumatic event occurs (significant symptoms within a month result in a diagnosis of acute stress disorder). A diagnosis of delayed-onset PTSD, on the other hand, requires that 6 months pass between the occurrence of the stressful event and the moment at which the individual develops PTSD (click here to see an earlier post in which we discussed the symptoms of PTSD and potential changes to the diagnosis in the upcoming DSM-V).
Despite the fact that immediate-onset and delayed-onset PTSD are explained in the DSM, we actually know very little about whether these two presentations actually differ from one another in meaningful ways or what causes one person to develop PTSD immediately after a trauma and another to develop those symptoms much later (or never at all). In order to help clarify this issue, Andrews and her colleagues (2009) recruited a large sample of veterans from the United Kingdom Service Personnel and Veterans Agency (SPVA) who were receiving pensions for PTSD or physical disabilities. In order to be included in the study, participants needed to be less than 60 years of age, must have encountered a traumatic event during military service, and had to suffer from either PTSD or a physical disability as a result of their military service. In total, 142 veterans were interviewed for this study and included in the analyses.
In order to determine whether an individual truly met criteria for PTSD during their lifetime, the authors administered structured diagnostic interviews to each participant. Depression and alcohol use disorders were also assessed using this method. In addition, each participant filled out a number of questionnaires that detailed their history of traumatic experiences and their responses to those traumas. After analyzing their results, the authors reported finding 40 cases of immediate-onset PTSD, 63 cases of delayed-onset PTSD, and 39 cases of no PTSD.
Veterans whose PTSD was delayed tended to meet PTSD criteria 1 to 2 years after the trauma whereas immediate-set typically occurred one month post-trauma. Importantly, 44% of the veterans who developed delayed-onset PTSD exhibited some PTSD symptoms before they even encountered their main traumatic event and 78% had developed some PTSD symptoms within 6 months of the traumatic event. The symptoms tended to develop gradually, meaning the delayed-onset PTSD rarely, if ever, appeared out of the blue with no warning signs (only 10% of the delayed-onset cases were symptom free 6 months post trauma). Instead, it appears that in these cases, some PTSD symptoms developed early on and, over time, their number and severity increased to the point that a diagnosis became warranted.
The time at which the symptoms onset is not the only interesting question to consider here, however, and Andrews and her colleagues (2009) took their analyses further than that. They also assessed which symptoms tended to come first and found that hyperarousal symptoms (e.g., difficulty falling asleep, anger outbursts, exaggerated startle response) were typically the first symptoms to emerge. The first re-experiencing symptoms tended to be nightmares and the first avoidance symptoms tended to be the avoidance of thoughts and feelings related to the traumatic event. These symptoms tended to be followed by detachment from other people and the other re-experiencing symptoms (e.g., flashbacks) and then the remaining avoidance and numbing symptoms (e.g., anhedonia, restricted range of emotions) and the loss of concentration. Quite clearly, this description depicts a steady decline in mental health and an increasingly severe presentation.
The authors' next group of analyses centered on comparing the three groups (immediate-onset, delayed-onset, and no onset) to one another. They found that delayed-onset individuals exhibited symptoms prior to the main trauma more often than did immediate-onset individuals. Additionally, although the two groups had the same number of symptoms, the delayed-onset group actually had a greater number of symptoms prior to onset than did the immediate-onset group. No particular PTSD symptom was more common in one PTSD group than in the other. The three groups demonstrated equal rates of alcohol abuse at the time of the interview; however, the delayed-onset group had higher rates of alcohol abuse and depression while still in service. Using a self-report questionnaire, the authors found that the PTSD groups experienced a higher number of traumatic events; however, the structured diagnostic interviews indicated that all three groups experienced the same number of traumas. The delayed-onset group experienced more combat events and war-zone trauma than did the immediate-onset group and both PTSD groups had higher numbers of such events than did the no-PTSD group; however, once the number of deployments was taken into consideration, these differences disappeared. The two PTSD groups did not differ from one another but were more likely than the no-PTSD group to respond to their traumatic event with intense fear, helplessness, or horror. The immediate-onset PTSD group, on the other hand, was the most likely to dissociate during the event and to experience shame and anger. The delayed-onset group actually demonstrated lower levels of shame, anger, and dissociation than the no-PTSD group. In their final analysis, the authors compared the year leading up to the diagnosis in delayed-onset cases with a similar time frame for no-PTSD cases and found that, while delayed-PTSD cases were no likely to encounter minor life stress during that 12-month stretch, they were significantly more likely to encounter major life stress.
All right, that was admittedly a lot of information and, if you're having a hard time keeping it all straight in your head, that's entirely understandable. It took me several readings of the paper to fully grasp everything the authors found. That being said, let me try to summarize the information in a more digestible format and quickly discuss the implications of the findings:
- Delayed and immediate-onset PTSD cases were equivalent in severity and involved identical symptoms.
- Delayed-onset PTSD involved the development of some symptoms prior to the main stressful event and a steady accumulation of more symptoms over time.
- Hyperarousal symptoms such as difficulty sleeping and a heightened startle response tend to be the first symptoms to appear in delayed-onset cases.
- Delayed-onset PTSD cases typically exhibited lower levels of dissociation, anger, and shame immediately following the traumatic event than did the immediate PTSD and no-PTSD groups.
- Delayed-onset PTSD cases generally experienced greater levels of major life stress in the year leading up to their diagnosis than did no-PTSD cases, but were no different in levels of minor life stress.
So, what does this all mean? Essentially, delayed-onset PTSD appears to be a gradual decent into mental illness rather than a sudden an unexpected turn of events. Additionally, it appears that delayed-onset PTSD may be the result of accumulating life stress that exacerbates symptoms of PTSD that were already present. In other words, such individuals might start to experience PTSD symptoms early on and never fully return to baseline. As they encounter more severely stressful life events, these early symptoms become more severe. As a result, even though the new life stress (e.g., divorce or unemployment post-deployment) may not relate to the original traumatic event, the symptoms may still reflect that original trigger.
As is the case with any study, there are some important limitations to consider here, the most important of which was the reliance upon retrospective recollections of the severity and chronology of symptoms. Additionally, given the overall lack of research on delayed-onset PTSD, it is important to remember that this is only one study and the results need to be replicated independently in order for us to be fully confident that they reflect reality. That being said, this was a truly impressive piece of work and we can learn a lot from these data. Studies like this help us to understand why mental illnesses look different in different people and who is vulnerable to which presentation. By understanding such things, we can work to prevent mental illness before it occurs and to make sure that treatments are better geared towards individuals.
If you would like to learn more about PTSD and its treatment, we recommend the following items, each of which is available through our online store for scientifically-based psychological resources:
- Prolonged Exposure Therapy for PTSD: Emotional Processing of Traumatic Experiences Therapist Guide by Edna Foa, Elizabeth Hembree, and Barbara Rothbaum
- Cognitive Processing Therapy for Rape Victims: A Treatment Manual by Patricia Resick and Monica Schnicke
Reclaiming Your Life from a Traumatic Experience: A Prolonged Exposure Treatment Program Workbook
by Barbara Rothbaum, Edna Foa, and Elizabeth Hembree
- Remembering Trauma by Richard McNally
- Prolonged Exposure Therapy for Adolescents with PTSD Emotional Processing of Traumatic Experiences, Therapist Guide by Edna Foa, Kelly Chrestman, and Eva Gilboa-Schechtman