Mental health articles

Epidemiologic studies are empirical sources of information about risk factors for PTSD—preexposure factors, exposure characteristics, and postexposure factors that are believed to be related to the probability of an individual developing PTSD following exposure to a potentially traumatic event. A small number of general population studies have examined risk factors for PTSD. General population studies have focused primarily on the role of preexposure factors in the development of PTSD. Studies also examined risk factors for PTSD among individuals exposed to specific types of stressors. The most consistently reported preexposure risk factors for PTSD among individuals who experienced a potential trauma include female gender, preexisting psychiatric disorder, family history of psychopathology, and prior exposure to trauma including abuse in childhood. Within classes of potentially traumatic stressors, characteristics of the stressor exposure also influence risk for developing PTSD. Postexposure factors, including postexposure social support and exposure to other potentially traumatic events, also affect the risk for PTSD. Epidemiologic studies in the United States have generally found higher rates of PTSD in women than in men. These findings for PTSD are consistent with gender differences reported for other anxiety disorders and major depression. This gender difference is not due to higher overall rates of exposure to potentially traumatic events among women. Data from community surveys indicate that men are more likely than women to be exposed to potential traumas. At the same time, the types of potential traumas that men and women experience may differ. For example, studies consistently find that women are more likely than men to experience sexual victimization. Differences in the types of traumas to which men and women are exposed may partially account for gender differences in the rates of PTSD. However, in both the Detroit Area Survey of Trauma and the NCS, the probability of PTSD among respondents reporting exposure to a potential trauma was two to four times higher in women than men, even after statistically adjusting for gender differences in the distribution of trauma types. Note that these findings do not rule out the possibility that gender differences in the characteristics of stressors experienced within broad categories of trauma types may contribute to the higher rates of PTSD observed among women. Among both men and women, preexisting psychiatric disorder and a family history of psychiatric disorder are associated with increased risk for PTSD following exposure to a potentially traumatic event. In the NCS, preexisting anxiety disorder and preexisting affective disorder were associated with PTSD in men and women, respectively, even after statistically adjusting for the nature of the index trauma. Consistent with these findings, in Breslau et al.’s sample of urban young adults, the probability of developing PTSD among individuals reporting exposure to a potential trauma was more than twofold for those with a preexisting anxiety disorder or preexisting major depression. With respect to family history, Breslau et al. found that the risk of developing PTSD from exposure to a potential trauma was significantly higher among individuals who reported a family history of anxiety, depression, psychosis, or antisocial behavior. (A family history of substance abuse did not increase vulnerability to PTSD in this sample.) In addition to conferring increased risk for future exposure on such events, past exposure to potentially traumatic events elevates the risk of developing PTSD upon exposure to a subsequent trauma. In the NWS, for example, women who reported exposure to multiple potentially traumatic events were more likely to receive a PTSD diagnosis than women who reported only a single exposure. Findings from several studies conducted with military veterans suggest that prior physical or sexual abuse, including abuse in childhood, is a risk factor for developing PTSD following military service in a war zone. Research indicates that the number and type of stressor exposures and also the specific characteristics of the exposure can influence the risk of developing PTSD. Subjective characteristics of stressor exposures as well as objective characteristics of the stressor (e.g., experienced injury) have been considered, and both influence the development of PTSD. Studies conducted with Vietnam veterans were among the first to consider multiple aspects of exposure to a particular type of stressor rather than simply measuring exposure as a dichotomous variable. Indeed, these studies have repeatedly found associations between risk of PTSD and the degree and nature of war zone stressor exposure. Evidence for an association between stressor characteristics and PTSD prevalence rates are not limited, however, to studies of war zone stressor exposure. In the NWS, for example, the rate of lifetime PTSD among the women who reported assaults that involved both perceived life threat and injury (45.2%) was more than double that observed among assault survivors who reported neither perceived life threat nor injury (19%). In studying individuals exposed to the Mount St. Helens volcano eruption, Shore et al. found a strong association between proximity to the mountain and the effects of exposure. Among males, first-year postdisaster onset rates for the three stress-related disorders evaluated were 0.9% in nonexposed controls, 2.5% in the low exposure group, and 11.1% in the high exposure group. Onset rates for females in these groups were 1.9, 5.6, and 20.9%, respectively. Compared with research on preexposure factors and exposure characteristics, relatively few studies examined the role of postexposure factors in the development of PTSD. In one study L. King, D. King, Fairbank, & Adams used structural equation modeling to assess the contribution of postexposure factors to the development of PTSD in Vietnam veterans. Among the postexposure factors examined, postwar functional social support and stressful life events had direct effects on PTSD in both genders, as did structural social support for men. In this study, functional support was operationalized in terms of veterans’ perceptions of the availability of emotional and instrumental support. Structural support was operationalized by a measure of the size and complexity of the veterans’s social network. The impact on current PTSD of what King et al. referred to as ‘‘resilience factors’’ (e.g., hardiness) was also evaluated in this study. Consistent with these results, Fontana & Rosenheck found that homecoming experiences along with war zone stressor exposures were key correlates of PTSD among Vietnam veterans. Findings from a small number of studies suggest that social reactions that followed exposure to interpersonal violence may also affect the development of posttraumatic symptoms in civilian populations.

Tags: PTSD, risk