The Efficacy of Exposure Therapy for Anxiety-Related Disorders and Its Underlying Mechanisms: The Case of OCD and PTSD

The Efficacy of Exposure Therapy for Anxiety-Related Disorders and Its Underlying Mechanisms: The Case of OCD and PTSD
June 7, 2017 by
The Efficacy of Exposure Therapy for Anxiety-Related Disorders and Its Underlying Mechanisms: The Case of OCD and PTSD

The most widely used treatment for anxiety disorders of all kinds is exposure therapy, a process which works on the simple premise that exposing yourself to a feared situation, stimuli or memory removes the fear of it. This was one of the first research driven and scientifically tested psychological treatments to be developed and remains the most effective treatment for OCD, anxiety, phobias and many other disorders.

This review summarises the work of researcher Edna Foa and her colleagues over three decades on the development of theory and treatment for anxiety disorders, and how the analysis of treatment outcomes can be used to further refine the treatment process and come to a better understanding of anxiety disorders such as OCD and PTSD.

Early Views of Anxiety

Our understanding of anxiety disorders is highly influenced by the two-factor theory developed by Mowrer in the 1950s. This theory states that fears are learned by a process of classical conditioning- learning through association- and then maintained by operant conditioning or learning through consequences. Seeing something frightening triggers a fear response, causing you to associate that particular situation with fear. Exposing yourself to the feared stimulus without the fear response extinguishes this association.

An influential view of fear developed in the 1980s called Emotional Processing Theory states that fears are represented as a mental “structure” which contains all the information about the feared stimuli, your response to it, and the meaning of both the stimuli and your response. Being confronted with the feared stimuli activates the entire structure and brings all this information to mind.

The difference between normal fear and pathological fear under this definition is that normal fear is realistic and proportional to the danger a stimulus presents. So being afraid of a deadly snake would be an adaptive, useful fear, for example. Fear is pathological when it is out of proportion to the realistic danger of a situation, for example feeling terrified by a picture of a snake or from seeing one on TV.

Under the EPT view, therapy works by creating a new, healthier structure around the feared stimulus which becomes activated instead of the old, pathological structure. In order to modify the fear structure it must be activated- you must be in the presence of the thing that causes you fear. This is why so much of anxiety treatment and OCD treatment revolves around exposure- facing the thing you are afraid of to learn a more appropriate response.

Emotional Processing and PTSD

Many people who have experienced some form of traumatic event experience symptoms such as heightened anxiety, mentally re-experiencing the traumatic event and avoiding anything related to that trauma.

Most people recover from trauma by re-activating the fear structure around their traumatic event in such a way that does not produce further fear, such as through discussion and physically or mentally engaging with their trauma. As such the fear structure becomes re-written and levels of fear reduce over time. Individuals who do not continue to engage with the traumatic event never re-write the fear structure so any activation of it results in the same levels of fear. This is how post traumatic stress disorder (PTSD) can develop.

Treatment for PTSD: Prolonged Exposure

Patients suffering from PTSD are unable to fully process the traumatic event that caused their condition due to avoiding confronting anything that reminds them of it. The goal of Prolonged Exposure (PE) therapy is therefore to help PTSD sufferers emotionally process their traumatic memories through systematic exposure to their feared situations and memories.

Part of the fear structure for PTSD sufferers will be an association between feelings of fear and stimuli around them which are perfectly safe. These associations are formed during the traumatic event itself, such as a war veteran having a fear of driving on open roads after encountering an explosive device on such a road. These associations are un-learned and a more healthy association is learned through in vivo exposure: directly confronting the feared situation in order to see that there is nothing to fear.

PTSD patients will usually also avoid thinking or talking about their traumatic experiences for fear that doing so will be harmful. As such PE involves helping patients to confront their most feared memory through imaginal exposure. This form of mental exposure helps patients make sense of the memory, re-evaluate the beliefs they have about themselves because of it, and learn that recalling and facing the fear does not lead to any negative consequences.

Research has shown that PE is effective in treating PTSD in a variety of patients, including rape survivors, war veterans and women who suffered from sexual abuse as children. Further research has identified several factors which can contribute to effective OCD treatment using PE, including:

  • Reducing negative self-perceptions and beliefs about the world (eg “the world is dangerous” or “I am weak”)
  • Fear activation- the higher the levels of emotional engagement and fear during treatment, the more effective the treatment will be

Emotional Processing and OCD Symptoms

In patients with OCD there are several incorrect and unhelpful beliefs which form part of the fear structure. These include an overestimation of the odds of something bad happening (eg thinking you will certainly catch an infection from physical contact with someone if you don’t wash your hands) and an overestimation of the consequences of such an outcome (eg thinking you will die or become seriously ill). These beliefs are formed based on a lack of evidence to the contrary. And since people with OCD tend to continue avoiding their feared situations and make use of compulsions to remove any perceived danger, they never get to prove these beliefs wrong.

OCD Treatment using EPT

The compulsions used by OCD sufferers to suppress their fearful obsessive thoughts stop them from proving their feared beliefs wrong. Someone who is fearful of getting infected through physical contact will never learn that the odds of this are very low if they wash their hands after every encounter. Treatment for OCD therefore needs to expose patients to the feared situation while preventing them from performing their compulsion response. This technique is known as Exposure and Response Prevention (EX/RP).

Exposing someone to their feared situation modifies their fear structure and disproves the false beliefs that something terrible will happen if they are left in this situation without performing their compulsive ritual. In vivo exposure and imagination-based exposure can both be used as an OCD cure with equally impressive results. EX/RP has proven to be a highly effective treatment for OCD either in conjunction with medication or as a stand-alone treatment.

Ongoing research has identified numerous factors which can influence OCD treatment outcomes. One such factor is whether patients can specifically articulate what they think will happen if they don’t perform their compulsions. Many patients have specific beliefs about what will happen in the absence of their compulsions (such as getting sick) but many simply state a vague belief that “something bad will happen” or that things “just wouldn’t be right.” Similarly, some patients are fully aware of the nonsensical nature of their compulsions but feel compelled to continue on with them, while others genuinely feel that their compulsions are the only thing stopping bad things from happening to them. This lack of insight into the nature of compulsions and an inability to express expected outcomes are both linked to poorer treatment outcomes, so treatment should work to address this.

One interesting and important finding regarding OCD treatment is that EX/RP has been shown to effectively treat depression at the same time. Therefore it appears there is some relationship between OCD and depression, and reducing OCD symptoms can have a positive effect on depression.


This review highlights the relationship between theory, treatment and research. Understanding disorders such as OCD and PTSD using psychological theories leads to the development of effective treatments. Studying these treatments provides further data with which helps us understand which mechanisms within the treatment are most effective, allowing us to refine the theory and treatment procedure.

For more information on how to treat OCD or PTSD please contact us.

Source :

Authors: Edna B. Foa and Carmen P. McLean
Journal: Annual Review of Clinical Psychology
Source Title:The Efficacy of Exposure Therapy for Anxiety-Related Disorders and Its Underlying Mechanisms: The Case of OCD and PTSD
Publish Date: Mar, 16