Prolonged exposure therapy: past, present, and future

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  • The Cutting Edge

    DEPRESSION AND ANXIETY 28 : 10431047 (2011)


    Edna B. Foa, Ph.D., is a professor of Clinical Psychology in Psychiatry at the University ofPennsylvania and Director of the Center for the Treatment and Study of Anxiety. Dr. Foadevoted her academic career to study the psychopathology and treatment of anxiety disorders,primarily obsessivecompulsive disorder (OCD) and posttraumatic stress disorder (PTSD).Her research, aimed at delineating theoretical frameworks, targeted treatments, and treatmentmechanisms of pathological anxiety has been highly influential. She is currently one of theleading experts in the areas of PTSD OCD. The treatment program she has developed forPTSD sufferers has received the most evidence for its efficacy and has been disseminated in theUnited States and around the world.Dr. Foa has published 18 books and more than 350 articles and book chapters and has lecturedextensively around the world. Her work has been recognized with numerous awards and

    honors, among them the Distinguished Scientific Contributions to Clinical Psychology Award from the AmericanPsychological Association; Lifetime Achievement Award presented by the International Society for Traumatic StressStudies; Lifetime Achievement Award presented by the Association for Behavior and Cognitive Therapies; TIME 100most influential people of the world; 2010 Lifetime Achievement in the Field of Trauma Psychology Award from theAmerican Psychological Association; and the Inaugural International ObsessiveCompulsive Disorder FoundationOutstanding Career Achievement Award.

    As is apparent from its title, I will focus in this articleon prolonged exposure therapy (PE), a treatmentprogram developed specifically for posttraumatic stressdisorder (PTSD).[1] It is important to note, however,that PE has its roots in the long tradition of exposuretherapy for anxiety disorders, and in the conceptualiza-tion of these disorders and their treatment withinemotional processing theory (EPT).[2,3] Therefore, Iwill first discuss briefly how EPT views the psycho-pathology underlying anxiety disorders and themechanisms that are involved in exposure therapy forthese disorders. I will then describe how EPTexplainsthe psychopathology of PTSD and how PE addressesthis psychopathology. Next, I will describe the treat-ment program and summarize the empirical literaturethat supports its efficacy and effectiveness. Finally,I will discuss novel ways of using exposure therapy forPTSD.

    EXPOSURE THERAPY AND ITSTHEORETICAL FOUNDATIONExposure therapy is a set of treatment programs that

    are commonly used to reduce pathological fear andrelated emotions, such as guilt, common in posttrau-matic stress disorder (PTSD) and other anxietydisorders (e.g., obsessivecompulsive disorder). Duringexposure for pathological anxiety, patients intentionallyconfront feared, but otherwise safe, objects, situations,thoughts, sensations, and memories with the goal of

    reducing fear and other negative reactions to the sameor similar stimuli in the future.[4]

    Exposure procedures are divided into three primarytypes: in vivo (real life), imaginal, and interoceptive.The selection of the type of exposure is dictated by thepathological characteristics of a given disorder. It isalso often the case that several types of exposure areconcurrently used in exposure programs.The conceptualization of anxiety disorders was

    greatly influenced by Mowrers two-factor model,[5]

    which explained the acquisition of fear as involvingclassical conditioning, and the maintenance of theconditioned fear avoidance as involving and operantconditioning. Accordingly, avoidance prevents theorganism from extinction learning; that is, fromlearning that the CS no longer predicts harm. Mowrerstwo-factor model implies that therapy must notonly promote extinction through confrontationwith erroneously feared objects, but also eliminateavoidances that would impede extinction learning.In 1986, Foa and Kozak[3] developed emotional

    processing theory (EPT) in which they expanded on

    Correspondence to: Edna B. Foa, Center for the Treatment andStudy of Anxiety, University of Pennsylvania, 3535 Market Street, 6th

    Floor, Philadelphia, PA 19104. E-mail:

    No conflict of interest was declared.

    Published online in Wiley Online Library (

    DOI 10.1002/da.20907

    rr 2011 Wiley Periodicals, Inc.

  • these early learning accounts of anxiety and itstreatment by adopting Langs concept of the fear(emotional) structure,[6,7] to create a comprehensivemodel for understanding pathological anxiety and themechanisms involved in exposure therapy for anxietydisorders. According to EPT, a fear (emotional)structure is a program for escaping or avoiding dangerthat includes representations of feared stimuli, responses,and the meaning of stimuli and responses. This structureis activated by input that matches the information storedin the structure. Foa and Kozak[3] emphasized theimportance of meaning representations as distinguishingbetween normal and pathological fear structures whichunderlie the different anxiety disorders.Foa and Kozak[3] assert that psychological interven-

    tions known to reduce fear, such as exposure, achievetheir effects by emotional processing, the process bywhich accurate information is incorporated into thefear structure and modifies the pathological elements inthe structure. Influenced by modern learning theoriesthat conceptualize extinction as creating new associa-tions rather than modifying old associations,[8] Foa andMcNally[9] proposed that exposure therapy does notalter the existing pathological structure, but ratherforms competing structures that do not includepathological associations among stimulus, response,and meaning representations. For therapy to be success-ful, the new emotional structure needs to be more easilyretrievable when shared elements between the old andthe new structures are present; conversely, when the oldpathological structure is activated, relapse occurs.EPT specifies two conditions that are necessary for

    therapeutic fear reduction to occur. First, the fear(emotional) structure must be activated in order for itto be available for modification. Second, new informa-tion that is incompatible with the pathologicalelements of the fear structure must be available andincorporated into the pathological memory structure(or form a new nonpathological competing structure).Exposure is a convenient and efficient way to satisfythese two conditions: approaching feared, distressingbut safe stimuli is likely to activate the fear (emotional)structure and at the same time provide correctiveinformation about consequences of approaching thefeared stimuli (e.g., The small dog did not bite me,When facing the dog, my anxiety did not lastforever). The incorporation of realistic informationinto the fear structure is the essence of emotionalprocessing and explains why exposure effectively reducespathological emotions. EPTs emphasis on integration ofdisconfirming information as the mechanism of change isconsistent with Rescorla and Wagners[10] mathematicalmodel of classical conditioning in which learning resultsfrom the discrepancy between what is expected tohappen and what actually happens. This learningthen modifies future expectations, according tothe RescorlaWagner model, or meaning elementsaccording to EPT. For a detailed review of research insupport of EPT, see Gillihan and Foa.[11]


    Although individual anxiety disorders share somecommon elements, such as the belief that anxiety willlast forever in a feared situation, these disorders aredistinguished with respect to the specific pathologicalelements of the underlying fear structure.[2] Becauseactivation of the fear structure depends on the matchbetween the information that is presented and elementsof the fear structure, exposure interventions aretailored to the pathological elements that are char-acteristic of each disorder. Matching the exposure tothe disorder-specific fear structure should lead togreater fear reduction by promoting activation of thestructure and providing information that is incompa-tible with the key pathological elements of thestructure. Exposure techniques are also designed toeliminate characteristic avoidance behaviors, such assituational avoidance, safety behaviors, ritualizing, ordistraction, which would prevent emotional processingfrom occurring.In PTSD, the fear (emotional) structure associated

    with the traumatic memory is conceived as a specificpathological fear structure that include erroneousassociations among stimuli and response that werepresent at the time of the trauma and their meaning.First, the traumatic memory structure is thought to becharacterized by a particularly large number ofstimulus elements that are erroneously associated withdanger (e.g., All men are rapists), which renders thefear easily activated and is reflected in the perceptionthat the world is entirely dangerous. Second, therepresentations of how the person behaved duringand after the trauma as well as the presence of PTSDsymptoms become associated with the meaning of self-incompetence and inability to cope. These twoerroneous perceptions, The world is entirely danger-ous and I am completely incompetent, promoteavoidance of trauma-related thoughts, images, andsituations, which in turn prevents emotional processingand the resultant recovery.


    EFFICACY, AND EFFECTIVENESSPE for PTSD illustrates the way in which the

    particular exposure program developed for a specificanxiety disorder is informed by the nature of thepsychopathology underlying the disorder.[1,12] As notedabove, EPT conceptualizes chronic PTSD as a fai