In a study just published in the Journal of Abnormal Psychology, Jesse Cougle, Heidi Resnick, and Dean Kilpatrick (2009) reported fascinating findings with serious clinical implications regarding the long term consequences of particular PTSD symptoms. Specifically, the authors examined the relationship between particular symptoms clusters and exposure to different types of future traumatic events. I emphasized the word "future" here for obvious reasons - the central premise of their analyses was that symptoms caused by prior exposure to traumatic events might lead to behavioral changes that increase the likelihood for additional future traumas, a conclusion that is not intuitively obvious.
Prior research provided plenty of rationale for the authors' hypotheses. As mentioned in the Cougle et al (2009) article, several researchers have posited that PTSD symptoms interfere with individuals' abilities to detect danger and engage in behaviors aimed at self-protection (Orcutt, Erikson, & Wolfe, 2002). Additionally, studies have shown that PTSD symptoms predicted attentional difficulties with respect to attending to threat cues (Pineles, Shipherd, Welch, & Yoval, 2007). Additionally, although not universally consistent, some authors have found that PTSD symptoms mediate the relationship between childhood sexual abuse and sexual abuse as an adult. In other words, while having been sexually abused in childhood appears to be associated with an increased likelihood of being sexually abused as an adult, this relationship may be explained by PTSD symptoms that increase the likelihood of the later event. Also, Orcutt and colleagues (2002) found that PTSD symptoms partially mediated the relationship between combat exposure and later exposure to traumatic events in a sample of Gulf War veterans. In this study, the re-experiencing symptoms of PTSD were the strongest predictors of later trauma. The re-experiencing symptoms of PTSD can take several forms. For some individuals, they are characterized by frequent nightmares involving the traumatic event. For others, they involve visceral flashbacks involving hallucinatory sensory experiences that leave the individual feeling as though they are literally re-experiencing the traumatic event. Importantly, prior studies have found that the re-experiencing symptoms of PTSD are the PTSD symptoms most highly predictive of suicidal ideation (Nye & Bell, 2007), thus indicating that they are particularly problematic even relative to other symptoms.
These findings indicate that, among the many consequences of PTSD is an inability to effectively detect, focus on, and effectively avoid threat. As such, it makes sense that the authors anticipated that PTSD would predispose individuals to future traumatic events. To assess the validity of this belief, that authors used data from the National Women's Study (NWS; Resnick, Kilpatrick, Dansky, Saunders, & Best, 1993), a longitudinal telephone-based survey of over 4,000 women that included three time points and a comprehensive examination of individuals' mental health and history of traumatic experiences. In these analyses, the authors only included data from women who completed all three waves of data collection, which resulted in a total sample of 2,863 women with an average age of 44.85. The impressive sample size in this study was a valuable asset.
The results were highly consistent with the authors' expectations. Among their findings was a significant relationship between the re-experiencing symptoms of PTSD and subsequent victimization through interpersonal violence. Importantly, this was true only for incidents of violence perpetrated by individuals other than intimate partners. In other words, the re-experiencing symptoms of PTSD had no impact on the likelihood of intimate partner violence, but did increase the chances that the individual would later be assaulted by somebody other than an intimate partner. This relationship was statistically significant even when controlling for substance use, depression, and past exposure to traumatic events, so these variables do not better account for the findings. The authors argue that the intrusive nature of re-experiencing symptoms likely increases the difficulty of effectively scanning one's environment for threat cues. As such, individuals experiencing these symptoms might be less likely to avoid a dangerous situation because PTSD has diminished their capacity for effectively evaluating their immediate environment. 
Additionally, the authors reported that the hyperarousal symptoms of PTSD (e.g., excessively scanning environment for threat cues) significantly predicted later exposure to traumatic events that did not involve interpersonal violence. This finding was more difficult to explain, given that increased vigilance for threat cues would seemingly decrease the likelihood that an individual would approach a dangerous situation. One interpretation the authors gave was that hyperarousal may lead individuals to believe threat is omnipresent, thus diminishing their ability to distinguish between threatening and non-threatening cues.
So what important lessons can be learned from this study? The main take home point is that PTSD does not reflect the end result of trauma. Instead, it reflects a consequence of traumatic events that results in increased vulnerability to future trauma. In other words, individuals who develop PTSD after a traumatic event are at increased risk for additional future trauma, which could thus result in an increasingly severe degree of symptomatology. Although this study can not conclusively determine why such vulnerabilities are increased, these findings and those of prior studies indicate that PTSD impacts attention and threat cue evaluation in a way that leaves individuals suffering from this disorder less able to effectively evaluate and navigate their immediate environments. The relationship between specific symptom clusters and particular outcomes (e.g., re-experiencing symptoms predicting future non-intimate partner violence) highlights the importance of a thorough, systematic assessment of specific symptoms and the use of empirically supported treatments such as prolonged exposure and cognitive processing therapy to diminish these symptoms so as to reduce the vulnerability to future traumatic events.
If you are suffering from PTSD or know somebody who is, please refer to our EST clinics page for resources close to your area providing empirically supported treatments. This list is not exhaustive, so if your area is not listed, this does not mean services are not available near you. Additionally, 1-800-273-TALK is a free, 24/7, anonymous source for help.
If you are interested in learning more about PTSD and/or its treatment, we recommend the following products, all of which are available through our online store:
- Prolonged Exposure Therapy for PTSD: Emotional Processing of Traumatic Experiences Therapist Guide (Treatments That Work)
- Cognitive Processing Therapy for Rape Victims: A Treatment Manual (Interpersonal Violence: The Practice Series)
Mike Anestis is a doctoral candidate in the clinical psychology department at Florida State University
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