Research shows that ERP is the gold standard for treating OCD (Foa & McLean, 2016). ERP is based on Mowrer’s two-factor theory – which states acquisition of fears (e.g., touching doorknobs leads to contamination) involves classical-conditioning, while the maintenance of this pathological fear involves operant conditioning (e.g., repetitive washing of hands; Foa & McLean, 2016). The dominant mechanism of how ERP works in Mower’s two factor theory is Emotional-Processing-Theory (EPT; Kim et al., 2020). EPT proposes that habituation (e.g., fear reduction) is the key aspect of ERP’s efficacy (Foa et al., 2006). EPT states that people with OCD possess pathological fear structures comprised of: (1) conditioned-stimuli like doorknobs; (2) conditioned-responses to these conditioned- stimuli (e.g., constant washing of hands after touching doorknobs) and (3) fearful interpretations of stimuli (e.g., doorknobs carry disease; Olatunji et al., 2019). Moreover, repetitively washing hands after touching a doorknob prevents habituation, while exposure to touching doorknobs while preventing the compulsion (e.g., washing of hands) habituates the fear response over the course of clinical treatment (e.g., Foa, 2010). While fear structures proposed by EPT are not directly observable, evidence for habituation is measured from within and between-session reduction in fear (Foa & McLean, 2016). Habituation is commonly measured by clinicians using the Subjective-Units-of-Distress-Scale (SUDS; Wolpe, 1973). ERP requires both exposure to the conditioned-stimuli (e.g., doorknobs) and prevention of the conditioned response (e.g., not washing hands) to be undertaken concurrently during each treatment session (Foa & McLean, 2016).
ERP focuses on the premise that anxiety is not permanent when in contact with various conditioned stimuli, and during treatment, fears will habituate (Abramowitz et al., 2009). Successful ERP entails individuals experiencing lower levels of fear at the end of an exposure session (within-session habituation), and reduced fear when presented with the same condition stimuli (e.g., a doorknob) from previous exposure sessions (e.g., between-session habituation; Knowles & Olatunji 2019). ERP is guided by a widely used and comprehensive treatment manual to ensure a consistent and standardisation approach in clinical settings (Foa et al., 2012). ERP for OCD usually consists of 17 - 20 weekly sessions lasting from 90 to 120 minutes (Abramowitz et al., 2011). Client and therapist collaboratively construct a fear-hierarchy of anxiety inducing stimuli, commencing with the least feared first (e.g., doorknob at home) progressing to the most feared (e.g., doorknob at public restrooms; Foa & McLean, 2016).
ERP can be undertaken in a session with a clinician or between sessions (e.g., homework) in two mediums: (1) in-vivo exposure and (2) imaginal exposure (Foa et al., 2012). In-vivo exposure consists of direct contact with the feared stimuli (e.g., client touching a doorknob) and prevention of washing their hands so they can learn to cope with their anxiety. Imaginal exposure is undertaken when it is not possible or advisable to commence with in-vivo exposure. For example, the client might imagine contracting a disease because they handled a public restroom doorknob and did not wash their hands thoroughly to induce heightened anxiety.
Treatment for OCD consists of psycho-education where information about the disorder is explained to help provide a better understanding of what are contributing to these distressful symptoms. Firstline treatments for OCD are CBT and medication. While CBT has shown efficacy in treating OCD, over the past four decades Exposure Response Prevention (ERP) has been the treatment of choice. ERP focuses on a collaborative approach to introduce clients to confronting objects and thoughts that bring distress, versus avoidance, so they learn over time that anxiety is not permanent and will reduce or cease. For example, a person who touches a doorknob may have intrusive thoughts of being contaminated and becoming ill, resulting in extensive washing to help remove the perceived contamination from their hands. ERP would expose the person to touch the doorknob and then prevent hand washing to learn to sit with the anxiety, and over a period of time learn that touching door knobs does not lead to illness.
However, some people struggle with ERP and stop seeking treatment. There are also a few misconceptions in the psychology arena that ERP works by lowering anxiety over time, and other efficacy-based treatments are not comparable to ERP’s superior efficacy. Unfortunately, current research (meta-analyses and randomised controlled trails) over the past 10 years shows there are suitable alternatives to ERP that show comparable efficacy that can be added or used as alternatives in treatment. Lastly, the premises of ERP being based on anxiety reduction over time is also debatable, meaning clinicians should be investing in the latest research (e.g., Inhibitory learning Theory) to help maximise the therapeutic effects of ERP and treatment for people suffering OCD.
Cognitive models of OCD propose that maladaptive beliefs and faulty interpretations of intrusive thoughts or images are central in the maintenance of OCD (e.g., Rachman, 1997, Salkovskis, 1985). Cognitive Therapy (CT) does not use prolonged exposure activities like ERP but focuses more on challenging beliefs and interpretations that produce and maintain OCD symptoms (Rachman, 1997). CT for OCD employs collaborative strategies where clients learn to identify and modify maladaptive beliefs about their obsessions and compulsions (Steketee et al., 2019). Common maladaptive beliefs observed in OCD are: (1) inflated sense of responsibility and (2) overestimating the likelihood of harm (Salvkovkis, 1985). For example, individuals with OCD may believe touching a doorknob may lead to contracting a disease, producing further thoughts of being responsible for passing on a disease to a family member (e.g., inflicting harm on others). The distress produced by these thoughts result in compulsive washing behaviours to rid the hands of possible disease to attenuate the anxiety produced by these obsessions (Tolin, 2009).
CT includes behavioural experiments which possess minor conceptual overlap with ERP, like confronting the fear of touching doorknobs, however client and therapist don’t focus on habituation, but more on challenging beliefs about doorknobs harbouring life threatening diseases (Foa, 2010). Behavioural experiments are usually therapist-guided to help restructure maladaptive beliefs which maintain OCD symptoms (Foa, 2010). The primary goal of behavioural experiments is to determine the perceived likelihood the belief or thought will occur. Moreover, the anxiety-provoking situation (e.g., touching a doorknob) is used to gather information about doorknobs and germs and assist the client in restructuring the maladaptive beliefs to a less harmful and anxiety producing thought, so compulsive behaviours can be ceased (or reduced).
Belloch et al. (2008used RCT in comparing 29 adult treatment completers that were randomly assigned to either ERP (n = 13) or CT (n = 16) interventions. Results showed there was no significant difference between both ERP and CT groups at 24- and 52-week follow-up for change in: (1) Y-BOCS scores and (2) depressive scores as measured by the Beck Depression Inventory (BDI-II; Beck et al., 1996). Moreover, clinical improvement (e.g., clients Y-BOCS scores < 12 post-treatment) was evident for 81% of the CT group, versus, 69% for ERP, which is surprising as ERP is considered the “gold standard” for OCD treatment (Belloch et al., 2008). The authors suggest that CT and ERP may be equally effective for treating OCD in adult populations.
Wells' metacognitive theory (MCT; Wells et al., 2017) argues that thinking about intrusive thoughts, obsessions, and compulsions (e.g., termed metacognitions) are integral to the development and maintenance of OCD. Metacognitive beliefs are defined as thinking about thinking, where an OCD specific maladaptive metacognitive belief may be thinking that an obsession is the same as a behaviour (e.g., though-action fusion; Miegel et al., 2020). Figure 1 displays key tenants of MCT. For example, the thought of touching a restroom doorknob is the same as physically touching the doorknob (e.g., thought-action fusion), and if the individual does not wash their hands to remove the germs, harm may occur to others. Recent research has identified the need to focus on metacognitive beliefs in the treatment of OCD (for a review see Wilhelm et al., 2015). Moreover, MCT for OCD has been suggested as an alternative to ERP and CT as it allows the individual to modify metacognitions by noticing intrusive thoughts (e.g., obsessions) as just mental events, and not actual behaviours. Viewing obsessions as identical to actual behaviours, versus just mental states, produces worry and fear, leading to the belief that washing hands (e.g., compulsive act) is the only way to neutralize the fear associated with it (Fisher & Wells, 2008)
Like CT and ERP, MCT uses behavioural experiments, but these experiments are focused on the clients’ metacognitions and not: (1) habituation as seen in ERP or (2) confronting fears to challenge and modify beliefs as observed in CT. The behavioural experiments are undertaken collaboratively with a therapist. A study, using an intention-to-treat (ITT) RCT analysis with 79 adult clients with OCD, showed after eight weeks that scores on the Y-BOCS for the MCT group were significantly lower than the treatment as-usual group (Miegel et al., 2021). However, there was no change in depressive symptoms between groups, potentially suggesting low efficacy for MCT in reducing depressive symptoms. A recent intention-to-treat RCT of 90 adults with OCD compared the efficacy between ERP and MCT (Melchoir et al., 2023). There was no statistical between group difference at post treatment (15 weeks) for MCT and ERP on Y-BOCS scores and measures of depression (BDI-II), suggesting that MCT is comparable to ERP for both OCD and depressive symptoms. It is plausible that the non-significant finding may be due to limited power due to a small sample size, thus warranting larger studies to investigate MCTs effectiveness in OCD. A strength of the study was that a strict fidelity protocol was employed, where fidelity ensures treatments are delivered as intended and do not include other therapeutic techniques (e.g., challenging thoughts), which may reduce internal validity of the design (Shavitt et al., 2023)
In the past 10 years, there has been more focus on “third wave” psychotherapies, like Acceptance Commitment Therapy (ACT) in treating OCD (Twohig et al., 2018). While CT interventions focus on modifying and restructuring interpretations (e.g., a doorknob may trigger thoughts of contamination and possible sickness), “third wave” therapies like ACT are “response-focused”. Response focused is centred on changing the relationship between the obsessive thought and the ensuing emotional state (fear of the doorknob and disease; Twohig et al., 2018). Therefore, the emphasis of ACT for treatment in OCD is not to challenge maladaptive beliefs or interpretations but help individuals to learn to change their relationship to obsessions and compulsions so that they are not struggling with these experiences (Philip & Cherian, 2022). ACT is the most prominent among the third-wave psychotherapies for OCD treatment (Twohig et al., 2018). A systematic review of 16 studies that examined the efficacy of ACT in treating OCD reported that ACT produces a considerable reduction in OCD symptoms (e.g., reduction in Y-BOCS scores) however most studies: (1) compared ACT to waitlist conditions and (2) included clients using medication - selective serotonin reuptake inhibitors (SSRI; Phillip & Cherian, 2021). A recent RCT of 40 adults from Iran using ACT as the main intervention and ERP as a control condition found no significant difference between the two therapies at post-treatment (Zemestani et al., 2022). It is important to note that sample sizes for ERP (n = 12) and ACT (n = 13) were considered small and may have precluded detection of a smaller ES between comparisons. Moreover, assessment of the Y-BOCS was self-administered and not clinician rated possibly reducing the validity of results. Research on self-rated versus clinician-rated Y-BOCS is mixed, with lower scores reported on self-reported Y-BOCS (Storch et al., 2016), or no differences between self- or clinician-rated Y-BOCS (Hauschildt et al., 2019). Noteworthy, Hauschildt and colleague’s clinician rated Y-BOCS interviews were conducted over the telephone, and not face-to-face, suggesting these results may not reflect usual methodology undertaken in RCTs (e.g., face to face clinician ratings).
