**4.2 Theories**

It is important to understand some of the basic theories on posttraumatic stress disorder in order to appreciate how these theories have then been integrated into the current theories that are far more complex. This section will provide a brief introduction to stress response theory, theory of shattered assumption, conditioning theory, and information-processing theory. This section will be followed by a discussion about some of the current psychological theories, including: emotional processing theory, dual representation theory, and Ehlers and Clark's (2000) cognitive theory on posttraumatic stress disorder. This section will conclude with a discussion on the biological correlates of posttraumatic stress disorder. It must be noted that the majority of the research on the biological aspects of posttraumatic stress disorder comes from correlational studies. Inferences cannot be made as to whether the biological abnormalities existed before the trauma and acted as a vulnerability for acquiring the disorder or developed after being exposed to the trauma.

### **4.2.1 Basic psychological theories**

36 Post Traumatic Stress Disorders in a Global Context

an attempted rape while in the military, 8% experienced some form of sexual coercion, and 27% experienced unwanted sexual attention. The Department of Defense (2004) found that 71% of the women seeking treatment for posttraumatic stress disorder, who had served in the Vietnam War and subsequent wars, had been raped while in the military. Some of the risk factors that increase a female soldier's chance of being sexually assaulted include being between the ages of 17 to 24 years old, using alcohol, and past history of sexual assault

This section will discuss the mechanisms through which an individual develops posttraumatic stress disorder. Brief attention will be given to the nature of traumatic stressors and the linear progression from acute stress disorder to posttraumatic stress disorder. The primary emphasis of this section will be on the psychological and biological theories regarding what makes a person vulnerable to posttraumatic stress disorder and

Not every individual who experiences a traumatic event will subsequently develop posttraumatic stress disorder. As the name implies, posttraumatic stress disorder results from an experience with a traumatic stressor. Some of the stressors that can cause the disorder include: natural disasters, combat, sexual assault, physical assault, abuse or neglect as a child, car accidents, surgery, and witnessing something life threatening happen to a loved one. A person can develop posttraumatic stress disorder from a single stressor or may encounter multiple traumatic situations. An individual who encounters multiple events may either develop the disorder after the first event and the subsequent events then exacerbate their symptoms or they may develop the disorder only after experiencing multiple

As previously discussed, an individual must experience their symptoms for at least a month in order to receive a posttraumatic stress disorder diagnosis (American Psychiatric Association, 2000). Individuals with symptoms lasting less than a month are given an acute stress disorder diagnosis. Although everyone who has posttraumatic stress disorder has also had acute stress disorder, not everyone who experiences acute stress disorder will go on to develop posttraumatic stress disorder. The diathesis-stress model helps explain why some individuals do not develop the disorder after a traumatic experience (Elwood et. al., 2009). This model refers to the interaction between a person's environment (the severity of the stressors that they encounter) and their biological and psychological predispositions, which can create vulnerability for developing the disorder. Those with high diathesis only require a minimal stressor in order to develop the disorder, whereas someone with no diathesis may never develop the disorder even when presented with an extreme stressor. The next section will present the psychological and biological theories on the characteristics that may act as a

It is important to understand some of the basic theories on posttraumatic stress disorder in order to appreciate how these theories have then been integrated into the current theories that are far more complex. This section will provide a brief introduction to stress response

**4.1 From trauma to acute stress disorder to posttraumatic stress disorder** 

(Williams & Bernstein, 2011).

what maintains it after symptoms arise.

diathesis for developing posttraumatic stress disorder.

**4. Etiology** 

traumatic events.

**4.2 Theories** 

*Stress response theory* posits that a person develops posttraumatic stress disorder when they are unable to reconcile their beliefs about the world with what happened during the trauma (Horowitz 1976 & 1986 as cited in Brewin & Holmes, 2003). People have an internal working model of how the world operates and a traumatic experience often violates some of those core beliefs. When the individual is unable to logically integrate what happened to them within their world-view, defense mechanisms become activated to repress the trauma. The defense mechanisms at play are said to mimic many of the avoidance and numbing symptoms of posttraumatic stress disorder. Since a drive to reconcile the trauma with one's world-view still unconsciously exists, the person will experience intrusive reminders of the trauma to force them to cope with what happened. The individual will continue to experience these symptoms until they resolve the discrepancy, which is said to explain why some suffer from chronic posttraumatic stress disorder. Clearly, this theory is highly rooted in psychodynamic principles. Although it does not explain the full range of symptoms in those with posttraumatic stress disorder, stress response theory provided a framework for the theories that followed it.

The *theory of shattered assumptions* is very similar to stress response theory in that it places an emphasis on the individual's assumptions about the world. According to this theory, the assumptions that are said to be the most important to how a person responds to trauma include believing that: the world is a good place, what happens within the world makes sense, and that they are generally a good person and worthy of having good things happen to them (Janoff-Bulman, 1992). One of the initial assumptions of this theory was that those with the most positive beliefs about the world would also be the most severely impacted by trauma. Since this belief was disproved by the fact that previous trauma serves as a risk factor for developing posttraumatic stress disorder, the theory was revised to say that those who have previously been exposed to trauma have already had their view of the world shattered. Having this negative outlook makes them vulnerable for developing posttraumatic stress disorder in the future. Similar to stress response theory, this theory provides an incomplete rationale for all of the symptoms associated with posttraumatic stress disorder.

The *conditioning theory* of posttraumatic stress disorder is based upon Mowrer's two-factor learning theory (1960 as cited in Brewin & Holmes, 2003). The process of fear acquisition occurs when a traumatic experience is paired with a neutral stimulus, resulting in a fear response to the previously neutral stimuli. Once the neutral stimulus becomes a conditioned stimulus, the person begins to generalize their fear to other situations (Keane, et. al., 1985 as cited in Brewin & Holmes, 2003). Using a behavioral framework, individuals with posttraumatic stress disorder should habituate to their feared stimuli due to the re-

Combat Related Posttraumatic Stress Disorder –

situations that remind them of the memory.

increased susceptibility to future danger.

the memory.

History, Prevalence, Etiology, Treatment, and Comorbidity 39

stress disorder. Positive views include believing the world is very safe or the person thinking they are completely capable of dealing with stress. Negative views would include believing that the world is a bad place or that bad things always happen to them. When an individual with rigid negative views of the world encounters a traumatic situation, it confirms that their views of the world were accurate. Therefore, an individual's outlook before experiencing trauma can impact how they perceive the event while it is happening and how they reflect on what happened. This theory is clinically relevant because if during treatment, an individual can be repeatedly re-exposed to the traumatic experience they can habituate to the feared stimulus and may reevaluate and hopefully reconsider how they reflect on the trauma. A client can be re-exposed to the trauma in session by either asking the client to imagine the experience or ask them to have real life encounters with innocuous

*Dual representation theory*, as its name implies, makes the assumption that people store memories in two distinct ways (Bewin et. al., 1996 as cited in Brewin & Holmes, 2003). More specifically, memories tied to emotionally traumatic situations are stored differently than those from every day occurrences. Memories can either be stored as *verbally accessible* or *situationally accessible*. A verbally accessible memory is one that can be intentionally retrieved. A situationally accessible memory cannot be recalled at will, and can only be triggered by perceptual reminders of the trauma, such as sights, sounds, or physiological responses. When a memory becomes pathological, it is because it has become dissociated from being verbally accessible and is only situationally accessible. In addition, only primary emotions are stored in situationally accessible memories, such as fear, hopelessness, or horror. In order to transform a traumatic memory into a normal one, the individual must learn to express the traumatic situation verbally as though it were regarding a daily occurrence. This changes the emotions associated with the situational memory from negative emotions to positive ones due to the continued pairing of positive emotions with

Ehlers and Clark (2000) proposed a *cognitive model of posttraumatic stress disorder*, which highlights the discrepancy of the disorder from other anxiety disorders. This is because individuals who develop posttraumatic stress disorder perceive a current threat from a past event instead of a future event. Furthermore, this theory suggests that what distinguishes those who develop posttraumatic stress disorder from those who experience trauma but do not develop the disorder, is whether they equate experiencing past trauma to also having an

Ehlers and Clark's model proposes that there are multiple negative appraisals that people can make after experiencing a traumatic event that may lead to the belief that there is also a current threat for danger. The content of the appraisals include an individual's beliefs regarding: the fact that the event occurred and that it happened to them, their behavior and emotions during the trauma, the meaning of initial occurrence of posttraumatic stress disorder symptoms and the chronic symptoms (such as re-experiencing, emotional numbing, and concentration problems), the positive and negative reactions of other's to the trauma, and the physical or global consequences of the trauma (Ehlers & Clark, 2000, pg. 322). Many of the negative appraisals that can lead to posttraumatic stress disorder contain themes about the individual assuming personal responsibility for the trauma, believing that others perceive the event as their fault, and assuming that their cognitive and emotional responses to the trauma are going to be permanent. Since individuals with posttraumatic

experiencing symptoms of the disorder. Individuals with the disorder do not habituate because once they begin re-experiencing the trauma they then engage activities that are consistent with the avoidance or numbing symptoms of the disorder. Since their distress subsides, they are then reinforced to continue engaging in avoidance and numbing tactics to cope with the trauma. Although this theory is highly useful for explaining posttraumatic stress disorder in many ways, it has been criticized because it is missing the cognitive component of the disorder. The cognitive component is important because it is often necessary for explaining individual differences in acquisition of the disorder (Brewin & Holmes, 2003).

*Information processing theory* integrates the cognitive components of the disorder into conditioning theory (Lang et. al., 1979 as cited in Brewin & Holmes, 2003). The general assumption of this theory is that when a person has a traumatic experience, the memory is stored differently than those from normal experiences. Posttraumatic stress disorder is then the result of a memory not being processed correctly. Information processing theory focuses solely on the cognitive components of the trauma and does not broadly integrate the social and personal context of the event. The memory of the trauma is comprised of: the surroundings during the trauma, other concrete aspects of the event, the person's physical and emotional reactions, and their assessment of the event. The consolidation of the experience, including all of the aforementioned components into a memory is called a *fear network.* Subsequently, when an individual is exposed to something that resembles an aspect of the fear network, the entire network then gets activated which triggers the same emotional response that was experienced during the trauma. An example of the fear network is a soldier ducking to the ground in fear when he hears a balloon pop because he was traumatized after witnessing an explosion while in combat. In this example, a loud noise, feeling fearful, and ducking to the ground, all are a part of the soldier's fear network. Simply hearing a sound that was similar to an explosion was sufficient to trigger the entire fear network.

Edna Foa added to this theory by explaining that what separates posttraumatic stress disorder from other anxiety disorders is that a traumatic event causes the person to question their basic assumptions about their personal safety in a global manner (Foa et. al., 1989 as cited in Brewin & Holmes, 2003). Since their assumptions about safety have been violated, their threshold to activate the fear network is low. In addition, because the individual does not feel safe, they are much more aware of their surroundings causing a reciprocal relationship between the decreased threshold and their sense of safety. An individual can reintegrate the different components of their fear network back into a normal memory if they are exposed to those components in a way that teaches them to that they are not actually in danger. This concept will re-visited and elaborated upon in the therapy section regarding Prolonged Exposure.

### **4.2.2 Contemporary psychological theories**

*Emotional processing theory* is based on information processing theory, but takes into consideration individual perceptions before, during, and after the trauma (Foa & Riggs, 1993 as cited in Brewin & Holmes; Foa & Rothbaum, 1998 as cited in Brewin & Holmes). Furthermore, this theory proposes that those with more rigid views before the trauma will have worse outcomes following the experience. Having an extremely positive view or extremely negative view pre-trauma is considered a risk factor for developing posttraumatic

experiencing symptoms of the disorder. Individuals with the disorder do not habituate because once they begin re-experiencing the trauma they then engage activities that are consistent with the avoidance or numbing symptoms of the disorder. Since their distress subsides, they are then reinforced to continue engaging in avoidance and numbing tactics to cope with the trauma. Although this theory is highly useful for explaining posttraumatic stress disorder in many ways, it has been criticized because it is missing the cognitive component of the disorder. The cognitive component is important because it is often necessary for explaining individual differences in acquisition of the disorder (Brewin &

*Information processing theory* integrates the cognitive components of the disorder into conditioning theory (Lang et. al., 1979 as cited in Brewin & Holmes, 2003). The general assumption of this theory is that when a person has a traumatic experience, the memory is stored differently than those from normal experiences. Posttraumatic stress disorder is then the result of a memory not being processed correctly. Information processing theory focuses solely on the cognitive components of the trauma and does not broadly integrate the social and personal context of the event. The memory of the trauma is comprised of: the surroundings during the trauma, other concrete aspects of the event, the person's physical and emotional reactions, and their assessment of the event. The consolidation of the experience, including all of the aforementioned components into a memory is called a *fear network.* Subsequently, when an individual is exposed to something that resembles an aspect of the fear network, the entire network then gets activated which triggers the same emotional response that was experienced during the trauma. An example of the fear network is a soldier ducking to the ground in fear when he hears a balloon pop because he was traumatized after witnessing an explosion while in combat. In this example, a loud noise, feeling fearful, and ducking to the ground, all are a part of the soldier's fear network. Simply hearing a sound that was similar to an explosion was sufficient to trigger the entire

Edna Foa added to this theory by explaining that what separates posttraumatic stress disorder from other anxiety disorders is that a traumatic event causes the person to question their basic assumptions about their personal safety in a global manner (Foa et. al., 1989 as cited in Brewin & Holmes, 2003). Since their assumptions about safety have been violated, their threshold to activate the fear network is low. In addition, because the individual does not feel safe, they are much more aware of their surroundings causing a reciprocal relationship between the decreased threshold and their sense of safety. An individual can reintegrate the different components of their fear network back into a normal memory if they are exposed to those components in a way that teaches them to that they are not actually in danger. This concept will re-visited and elaborated upon in the therapy section

*Emotional processing theory* is based on information processing theory, but takes into consideration individual perceptions before, during, and after the trauma (Foa & Riggs, 1993 as cited in Brewin & Holmes; Foa & Rothbaum, 1998 as cited in Brewin & Holmes). Furthermore, this theory proposes that those with more rigid views before the trauma will have worse outcomes following the experience. Having an extremely positive view or extremely negative view pre-trauma is considered a risk factor for developing posttraumatic

Holmes, 2003).

fear network.

regarding Prolonged Exposure.

**4.2.2 Contemporary psychological theories** 

stress disorder. Positive views include believing the world is very safe or the person thinking they are completely capable of dealing with stress. Negative views would include believing that the world is a bad place or that bad things always happen to them. When an individual with rigid negative views of the world encounters a traumatic situation, it confirms that their views of the world were accurate. Therefore, an individual's outlook before experiencing trauma can impact how they perceive the event while it is happening and how they reflect on what happened. This theory is clinically relevant because if during treatment, an individual can be repeatedly re-exposed to the traumatic experience they can habituate to the feared stimulus and may reevaluate and hopefully reconsider how they reflect on the trauma. A client can be re-exposed to the trauma in session by either asking the client to imagine the experience or ask them to have real life encounters with innocuous situations that remind them of the memory.

*Dual representation theory*, as its name implies, makes the assumption that people store memories in two distinct ways (Bewin et. al., 1996 as cited in Brewin & Holmes, 2003). More specifically, memories tied to emotionally traumatic situations are stored differently than those from every day occurrences. Memories can either be stored as *verbally accessible* or *situationally accessible*. A verbally accessible memory is one that can be intentionally retrieved. A situationally accessible memory cannot be recalled at will, and can only be triggered by perceptual reminders of the trauma, such as sights, sounds, or physiological responses. When a memory becomes pathological, it is because it has become dissociated from being verbally accessible and is only situationally accessible. In addition, only primary emotions are stored in situationally accessible memories, such as fear, hopelessness, or horror. In order to transform a traumatic memory into a normal one, the individual must learn to express the traumatic situation verbally as though it were regarding a daily occurrence. This changes the emotions associated with the situational memory from negative emotions to positive ones due to the continued pairing of positive emotions with the memory.

Ehlers and Clark (2000) proposed a *cognitive model of posttraumatic stress disorder*, which highlights the discrepancy of the disorder from other anxiety disorders. This is because individuals who develop posttraumatic stress disorder perceive a current threat from a past event instead of a future event. Furthermore, this theory suggests that what distinguishes those who develop posttraumatic stress disorder from those who experience trauma but do not develop the disorder, is whether they equate experiencing past trauma to also having an increased susceptibility to future danger.

Ehlers and Clark's model proposes that there are multiple negative appraisals that people can make after experiencing a traumatic event that may lead to the belief that there is also a current threat for danger. The content of the appraisals include an individual's beliefs regarding: the fact that the event occurred and that it happened to them, their behavior and emotions during the trauma, the meaning of initial occurrence of posttraumatic stress disorder symptoms and the chronic symptoms (such as re-experiencing, emotional numbing, and concentration problems), the positive and negative reactions of other's to the trauma, and the physical or global consequences of the trauma (Ehlers & Clark, 2000, pg. 322). Many of the negative appraisals that can lead to posttraumatic stress disorder contain themes about the individual assuming personal responsibility for the trauma, believing that others perceive the event as their fault, and assuming that their cognitive and emotional responses to the trauma are going to be permanent. Since individuals with posttraumatic

Combat Related Posttraumatic Stress Disorder –

inferences from these results.

exaggerated stress response.

particular client.

**5. Treatment** 

History, Prevalence, Etiology, Treatment, and Comorbidity 41

result of hyperactivity in the amygdala. They also discovered that high-risk twin pairs often had some level of neurological dysfunction. The study inferred that this preexisting dysfunction might act as a vulnerability for developing posttraumatic stress disorder. When examining hippocampal volume using magnetic resonance imaging, they found that the twins with more severe posttraumatic stress disorder had a smaller hippocampus than average, but their twin brothers also had reduced hippocampal volume. Since this is a correlational study, the authors caution that more research is needed to draw causal

Stress hormones such as cortisol have also been examined and found to correlate with posttraumatic stress disorder. A meta-analysis by de Kloet and colleagues (2006) concluded that those with posttraumatic stress disorder have lower baseline levels of cortisol than those without the disorder. Conversely, when exposed to a stressor, those with the posttraumatic stress disorder show an elevated cortisol response in comparison to those without the disorder. Although many theories have been proposed as to why this relationship exists, there is no conclusive evidence explaining why people with posttraumatic stress disorder have deceased baseline levels of cortisol, yet have an

In accordance with the diathesis-stress model, both the psychological and biological theories on posttraumatic stress disorder should be taken into consideration because diathesis is comprised of both components. All of the contemporary theories on posttraumatic stress disorder are valuable to help conceptualize the disorder and no one theory has become dominant within the research. Each theory can be applied based on its relevance to a

A number of treatments have been shown to be effective in treating posttraumatic stress disorder. Many of the treatments that are used for the disorder are rooted in cognitive behavioral therapy. This section will focus primarily on the treatments that have proven effective with those suffering from combat related posttraumatic stress disorder. The Veterans Administration in particular, has endorsed both cognitive processing therapy and prolonged exposure therapy (Karlin et. al., 2010). This section will also address a few of the more novel treatments for posttraumatic stress disorder such as the use of virtual reality and biofeedback. Some clinicians and researchers have recently incorporated virtual reality technology into prolonged exposure therapy. In addition, with the use of biofeedback, veterans can be taught to monitor their own physiological reactions, which are often

This section will discuss cognitive processing therapy, prolonged exposure therapy, and the medications that can be used for individuals with posttraumatic stress disorder. An array of therapies exists for treating posttraumatic stress disorder and what is covered below should

*Cognitive Processing Therapy* places an emphasis on the meaning that an individual assigns to their traumatic experience (Karlin et. al., 2010; Resick & Schnicke, 1992). The treatment is

elevated due to the hyper-arousal component of posttraumatic stress disorder.

**5.1 Popular treatments for combat related posttraumatic stress disorder** 

not be considered an all-inclusive list of the effective treatments.

**5.1.1 Cognitive processing therapy** 

stress disorder often assume personal responsibility for the trauma by attributing it's occurrence a personal deficiency, they also overestimate the likelihood of something dangerous happening again.

Ehlers and Clark's theory adopts some of the same concepts from dual representation theory and posits that a pathological memory contains only the sensory and emotional aspects of the event. Since the individual has not integrated the memory into their autobiographical memory, they are unable to provide all of the details of the event on cue. Remembering the details of the event may buffer from having unwanted recollections by providing context for memory. The chronological details of the event are also important because those with posttraumatic stress disorder may not be consciously aware of all of the precursors of the event, but can still be triggered by a stimulus that preceded the trauma. These individuals may also show biased attention for the negative aspects of what occurred before, during, and after the trauma. Furthermore, they often engage in behaviors that cause or exacerbate their symptoms, such as avoiding reminders of the trauma. Their avoidance often causes intrusive recollections, fails to give them the opportunity to disprove their beliefs about the trauma, and inhibits them from creating an autobiographical memory of the event. This theory provides the most integrative and detailed explanation of posttraumatic stress disorder and clearly incorporates many of the theories that preceded it. The theory's multifaceted explanation of posttraumatic stress disorder provides clinicians with a complex framework for viewing their clients. Due to the complexity of the theory, clinicians can choose which aspects are the most relevant to the cognitive distortions that they are seeing in their client.

#### **4.2.3 Biological theories**

In recent years, researchers have extended the biological theories on depression to posttraumatic stress disorder due to the comorbidity of both disorders. Kilpatrick and colleagues (2007) were one of the first research teams to generalize the genetic research on the serotonin transporter gene (5-HTTLPR) from depression to posttraumatic stress disorder. Previous research established that those with two short 5-HTTLPR alleles had a higher risk of developing depression than those with two long alleles or a combination of a short and long allele (Lesch et. al., 1996). The environment also plays a huge role in whether someone develops depression despite the genetic component of the disorder. Using this framework, Kilpatrick and colleagues (2007) investigated whether having two short 5- HTTLPR alleles increased the likelihood of developing posttraumatic stress disorder in participants who were exposed to hurricane Rita, which hit Florida in 2004. They found that low social support and high hurricane exposure proved to be risk factors for developing posttraumatic stress disorder. In addition individuals who had high levels of hurricane exposure, low levels of social support, and had two short alleles had a 4.5 times greater chance of developing posttraumatic stress disorder than the rest of the sample.

Research has also looked at monozygotic twins to examine the biological differences in a twin with posttraumatic stress disorder compared to their twin who does not have posttraumatic stress disorder. Pitman and colleagues (2006) examined twin pairs, where one twin obtained posttraumatic stress disorder through involvement in the Vietnam War and the other twin did not experience combat exposure or develop posttraumatic stress disorder. They found that the twin with posttraumatic stress disorder demonstrated higher heart rate reactivity to a startling noise than his brother. This response is thought to be in part the result of hyperactivity in the amygdala. They also discovered that high-risk twin pairs often had some level of neurological dysfunction. The study inferred that this preexisting dysfunction might act as a vulnerability for developing posttraumatic stress disorder. When examining hippocampal volume using magnetic resonance imaging, they found that the twins with more severe posttraumatic stress disorder had a smaller hippocampus than average, but their twin brothers also had reduced hippocampal volume. Since this is a correlational study, the authors caution that more research is needed to draw causal inferences from these results.

Stress hormones such as cortisol have also been examined and found to correlate with posttraumatic stress disorder. A meta-analysis by de Kloet and colleagues (2006) concluded that those with posttraumatic stress disorder have lower baseline levels of cortisol than those without the disorder. Conversely, when exposed to a stressor, those with the posttraumatic stress disorder show an elevated cortisol response in comparison to those without the disorder. Although many theories have been proposed as to why this relationship exists, there is no conclusive evidence explaining why people with posttraumatic stress disorder have deceased baseline levels of cortisol, yet have an exaggerated stress response.

In accordance with the diathesis-stress model, both the psychological and biological theories on posttraumatic stress disorder should be taken into consideration because diathesis is comprised of both components. All of the contemporary theories on posttraumatic stress disorder are valuable to help conceptualize the disorder and no one theory has become dominant within the research. Each theory can be applied based on its relevance to a particular client.
