“Ehlers & Clark (2000). A cognitive model of posttraumatic stress disorder.” – Article summary

Ehler and Clarke’s cognitive model of PTSD states that persistent PTSD only occurs if individuals process the traumatic event and/or consequences in a way which produces a sense of serious, current threat. People with persistent PTSD are unable to see the trauma as a time-limited event that does not have global implications for their future. There are two key processes that lead to this sense of threat:

• Individual differences in the appraisal of trauma and its consequences.
• Individual differences in the nature of the memory for the event and its link to other autobiographical memories.

The perception of current threat is accompanied by intrusions and other re-experiencing symptoms when activated. This motivates a series of behavioural and cognitive responses that are intended to reduce perceived threat and distress in the short-term but prevent cognitive change. This maintains the disorder.

There are several types of appraisal which can produce a sense of current threat:

• Overgeneralization of the event (i.e. perceive a range of normal activities as more dangerous than they really are, such as driving).
• Exaggerate the probability of further traumatic event (e.g. avoiding driving after car crash).
• Negative appraisal of one’s behaviour during the trauma (e.g. blaming oneself for not seeing the signs of the traumatic event earlier).

The interpretation of one’s initial PTSD symptoms (1), other people’s reactions in the aftermath of the trauma (2) and the appraisal of the consequences of the trauma in other life domains (e.g. physical consequences) (3) are important and can produce a sense of current threat. Initial PTSD symptoms are normal after a traumatic event. If people appraise this as being an integral part of the self, then they may conclude that the trauma has permanently changed them.

These appraisals maintain PTSD by directly producing negative emotions and by encouraging individuals to engage in dysfunctional coping strategies. The nature of the emotional response in PTSD depends on the appraisal:

• Appraisals concerning perceived danger lead to fear.
• Appraisals concerning others violating personal rules and unfairness lead to anger.
• Appraisals concerning one’s responsibility for the traumatic event lead to guilt.
• Appraisals concerning one’s violation of important internal standards lead to shame.
• Appraisals concerning perceived loss lead to sadness.

There are several characteristics of involuntary re-experiencing:

• Involuntary reexperiencing mainly consists of sensory impressions rather than thoughts.
• The sensory impressions are experienced as happening now rather than as memories.
• The original emotions and sensory impressions are reexperienced despite new information contradicting the original impression.
• The re-experiencing occurs without recollection of the event (i.e. only emotions and sensory impressions).
• The reexperiencing is triggered by a wide range of stimuli and situations.

The cues for reexperiencing do not need to have a strong semantic relationship to the trauma (e.g. a similar smell may be enough). The pattern of retrieval and the intrusion characteristics may exist due to the way trauma is encoded in memory.

Autobiographical information can be retrieved by purposefully remembering (i.e. higher-order meaning-based retrieval strategies) or direct triggering of a stimulus (e.g. stimulus that is associated with the event). Autobiographical memories are often elaborated by theme and personal time period. It thus contains specific information about the event and general information of the time period and this is recollected simultaneously. The elaboration enhances purposeful recollection and inhibits direct triggering of a stimulus as a form of recollection. In persistent PTSD, the trauma memory may be poorly elaborated and inadequately integrated into its context in time.

The stimulus-stimulus (i.e. S-S) and the stimulus-response (i.e. S-R) associations are particularly strong for traumatic information in PTSD. These associations help individuals make predictions about what will happen next. However, these associations lead to the sense that the traumatic event is happening again while this is not the case. This is partially the case because there is strong perceptual priming for stimuli that were temporally associated with the traumatic event.

There is a reciprocal relationship between the nature of the trauma memory and the appraisal of the trauma. This means that when people recall the trauma this is biased by their appraisals and they selectively retrieve information consistent with these appraisals. A trauma can thus disorganize autobiographical memory. This makes cue-driven recollections of the trauma more likely.

The strategy a person uses to control the sense of threat and PTSD symptoms is linked to the appraisal of the trauma. Negative appraisals may lead to maladaptive strategies (e.g. thought suppression) to control the symptoms and sense of threat. This maintains PTSD in three ways:

• The maladaptive strategies directly produce PTSD symptoms.
• The maladaptive strategies prevent change in negative appraisal of the trauma.
• The maladaptive strategies prevent change in the nature of the trauma memory.

Safety behaviours refer to actions individuals take to prevent or minimize anticipated further trauma (e.g. avoiding the highway). This prevents disconfirmation of the belief that another trauma will occur if one does not engage in these behaviours.

The appraisal of the trauma and the nature of the trauma memory is influenced by cognitive processing during the trauma. This depends on several factors:

• Characteristics of the trauma (e.g. duration, predictability).
• Previous experience of trauma and coping styles used during these events.
• Low intellectual ability (i.e. less conceptual processing).
• Prior beliefs.
• State factors (e.g. being drunk).

The nature of the trauma memory depends on the quality of processing during encoding. A lack of conceptual processing during the trauma makes that the trauma is more difficult to intentionally retrieve. The strong perceptual priming leads to a poor discriminability of the trauma memory and other memories leading to more reexperiencing symptoms. This emphasizes the need for conceptual processing.

A mental defeat refers to the perceived loss of all psychological autonomy, accompanied by a sense of not being human anymore. This influences the appraisal.

The cognitive model of PTSD explains several features of PTSD:

1. Delayed onset of PTSD
   This may occur because of a change in meaning of the trauma (e.g. exposure to potent reminder weeks after the trauma).
2. Anniversary reaction
   This may be explained by the combination of reminders and appraisals of the PTSD symptoms (e.g. weather and light conditions become more similar).
3. Frozen in time (i.e. feeling locked in the past)
   This can be explained by the appraisal of the event (1), the re-experiencing symptoms which causes one to feel disconnected from reality (2) and avoiding or giving up activities that were of importance to the individual prior to the trauma (3).
4. Sense of impending doom
   This can be explained by the nature of the trauma memory. This means that the sensory information and emotions are retrieved without the time perspective of autobiographical memories. This leads to a perception of future threat.
5. No benefit from talking/thinking about the trauma
   This may be due to how people talk and think about the trauma (e.g. rumination, non-emotional talking).

There are several requirements for successful treatment of PTSD:

• Elaborating and integrating the trauma memory in the context of the individual’s preceding and subsequent experience to reduce intrusive reexperiencing.
• Modification of negative appraisals of the trauma and its consequences.
• Modification of maladaptive behavioural strategies that prevent memory elaboration and exacerbate symptoms.

There are several procedures that may prove useful in the treatment of PTSD:

1. Assessment
   This aims to identify main cognitive themes which need to be addressed in therapy. It is imperative to identify what has been most distressing since the traumatic event and explore patient’s beliefs about the symptoms (1), future (2) and other people’s behaviour (3).
2. Rationale for treatment
   This includes explaining that PTSD symptoms are a normal reaction to an abnormal situation (1), explain that the coping strategies maintain PTSD (2) and explain that the goal of the treatment is fully processing the trauma (3).
3. Thought suppression experiment
   This includes illustrating the consequences of attempting to suppress thoughts.
4. Education
   This includes education to correct problematic appraisals.
5. Reclaiming one’s life
   This includes rediscovering activities which brought the patient joy before the trauma (e.g. tennis).
6. Reliving with cognitive restructuring
   This includes some form of reliving the trauma while changing the appraisals. This promotes elaboration and contextualization of the trauma memory but is emotionally draining. Cognitive restructuring should not occur when the patient is too exhausted to benefit.
7. In vivo exposure
   This includes exposure to avoided reminders of the trauma. This helps patients accept that the traumatic event is in the past.
8. Identifying triggers of intrusive memories and emotions
   This includes identifying triggers to discriminate the context of the stimulus (e.g. driving) then and the context of the stimulus now.
9. Imagery techniques
   This includes imagining other scenarios and allows patients to explore possible consequences of actions that were not taken.

There are several specific patient groups who may require extensive verbal and imagery cognitive restructuring:

• People who experience anger, guilt or shame as the predominant emotion.
• People who interpret their behaviour or emotions as something negative about themselves.
• People who experienced violence over a prolonged period of time.
• Rape victims who experienced mental defeat.

The effectiveness of reliving the trauma may be due to several aspects:

• It links previously unconnected parts of the traumatic experience (i.e. giving the trauma context).
• It facilitates the retrieval of elements of the trauma memory that are difficult for the patient to access otherwise.
• It facilitates the discrimination between then and now (i.e. more discrimination between the traumatic event and safe events).
• It may make it more difficult to retrieve the original sensory impressions from memory through verbalisation of the visual and other sensory cues.