Mechanisms of change in ERP treatment of compulsive hand washing: Does primary threat make a difference?

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Abstract

The present study sought to examine patterns of habituation in exposure and response prevention (ERP) treatment of compulsive hand washing. Sub-clinical compulsive washers (n=27) with illness or non-illness primary threats were compared in order to detect potential differences in response to a single session of ERP. Changes in anxiety, disgust, and urge to wash were analyzed, and significant reductions in both anxiety and disgust were noted. Urge to wash significantly declined among washers primarily concerned with illness; among those concerned with non-illness threats, urge to wash did not significantly decline. Moreover, anxiety was found to decline when controlling for disgust and vice versa. Lastly, when both anxiety and disgust were entered into a model predicting changes in urge to wash, anxiety but not disgust predicted urge to wash for those with illness-related threats; for washers with non-illness threats, the findings were the reverse. Several clinical and theoretical implications are discussed.

Introduction

Compulsive washing is one of the most common obsessive-compulsive disorder (OCD) subtypes. An effective psychological treatment for compulsive washing that has received much empirical support is exposure and response prevention (ERP). For washers, this technique involves contact with stimuli (e.g., a public toilet) that elicit the urge to wash. After the hands and/or other parts of the body have been “contaminated,” patients are asked to refrain from washing for an extended period of time. Repeated sessions of ERP are expected to result in reduction in anxiety and urge to wash both within- and across-sessions. This treatment modality has produced response rates of up to 86% among mixed samples of OCD patients (Foa et al., 2005).

Preliminary evidence indicates that the presence of washing compulsions predicts a less favorable response to ERP treatment (Coehlo & Whitttal, 2001). In addition, one investigation revealed that washers are less responsive to pharmacologic treatment than other OCD subtypes (Alarcon, Libb, & Spitler, 1993). Such findings suggest that work is needed in identifying maintaining factors in contamination fears and developing strategies for facilitating symptom reduction.

Evidence has recently accumulated demonstrating an association between disgust and contamination fear (Mancini, Gragnani, & D’Olimpio, 2001; Muris et al., 2000; Olatunji et al., 2004; Thorpe, Patel, & Simonds, 2003). For example, OC washers score significantly higher on animal and body product disgust relative to anxious and non-anxious controls and OC patients without washing concerns (Woody and Tolin, 2000). It has been postulated that the contribution of disgust sensitivity to anxiety disorder symptoms may be due to shared variance with anxiety (Muris, Merckelbach, Schmidt, & Sandy,1999; Thorpe & Salkovskis, 1998). However, disgust sensitivity has been shown to predict contamination fears even after controlling for trait anxiety and anxiety sensitivity (Olatunji, Sawchuk, Arrindell, & Lohr, 2005).

Fear and disgust have been researched most extensively in relation to anxiety disorders such as spider phobia (cf. Woody & Teachman, 2000). The association between spider fear and disgust led Smits, Telch, and Randall (2002) to investigate whether exposure treatment for spider phobia leads to decline in both fear and disgust. Using hierarchical linear modeling and within-session process measures, they found that exposure treatment contributed to reductions in both fear and disgust. However, fear declined more rapidly than disgust. Furthermore, fear and disgust were found to be partially independent of each other: fear significantly declined when controlling for changes in disgust, and vice versa.

Little research attention has been given towards examining patterns of change in ERP treatment of compulsive washing, and few studies have been carried out examining the impact of ERP on both anxiety and disgust. McKay (2006) found that anxiety declined more rapidly than disgust in ERP treatment of compulsive washing, but it remains unclear as to whether reductions in both are independent of each other or are uniquely predictive of changes in urge to wash. The present study was intended to address these questions by assessing disgust, anxiety, and urge to wash over the course of a 60-min ERP treatment session for sub-clinical compulsive washers. Sub-clinical washers were considered appropriate for use in this study, given that evidence suggests non-clinical samples exhibit obsessions, compulsions, and beliefs about intrusions that are similar to those found in clinical populations of OCD patients (see Gibbs, 1996, for a review). In addition, the effect of variables such as illness expectancies are similar in studies using both clinical (Jones & Menzies, 1997) and sub-clinical (Jones & Menzies (1998a), Jones & Menzies (1998b)) samples.

Jones and Menzies (1997) have argued that the perceived likelihood of becoming ill or diseased is the primary threat associated with compulsive washing. However, others have argued that different non-illness threats exist that could also contribute to compulsive hand washing. Foa and Wilson (2001), for example, suggest that OCD patients with fears of contamination may have a belief that their anxiety will last forever. This is consistent with findings showing elevated anxiety sensitivity among OCD patients relative to normal controls (Taylor, Koch, & McNally, 1992).

In addition, Rachman (1994) distinguished between washers who have their compulsions provoked either by illness concerns or anxiety regarding dirtiness. Fear, but not disgust, figures prominently in the former subtype while discomfort, fear, and disgust, are more characteristic of the latter subtype. More recently, Rachman (2004) distinguished between washers who have their compulsions triggered by fear of illness and those who have “mental health” as their main concern. These theoretical perspectives led us to examine differences between washers with illness- and non-illness-related primary threats through the analysis of patterns of change in anxiety, disgust, and urge to wash between these groups. Three specific questions were addressed:

  • 1.

    Do changes in anxiety, disgust, and urge to wash during ERP treatment differ between washers displaying illness as their primary threat vs. washers displaying non-illness-related primary threats?

  • 2.

    Does the decline in anxiety across trials remain significant after controlling for changes in disgust and vice versa?

  • 3.

    Do declines in disgust and anxiety uniquely predict decline in urge to wash?

Section snippets

Participants

Participants were recruited through an introductory psychology course at a large southwestern university. To be included in the study, participants had to score in the top 10 percent of the OCI-R (Foa et al., 2002) washing subscale (>4) and report an anxiety level of 50 or more on at least one of three behavioral approach tests (BATs). Of the 71 who completed the pre-treatment assessment, 54 were deemed eligible to participate in the treatment phase of the study, and 27 decided to participate.

Breakdown of participants’ primary threat

Of the 27 participants, 11 (40.7%) reported a primary threat of being overwhelmed by feelings of disgust, 10 (37.0%) reported concerns of illness or harm to self, 3 (11.1%) reported concern that their anxiety would never end, 2 (7.4%) reported that someone else would become ill or harmed in some way, and 1 (3.7%) said that he/she would lose control. Twelve (44.4%) reported concerns of either illness or harm to self/others and were thus categorized as having illness-related primary threats, and

Discussion

The present study revealed several findings regarding the effects of ERP on anxiety and disgust in individuals with contamination fear. Both anxiety and disgust significantly declined in the context of one session of ERP treatment. In addition, consistent with the findings of Smits et al. (2002), their decline appeared to be independent of each other: anxiety significantly declined when controlling for changes in disgust, and vice versa. Though disgust ratings at the beginning of the ERP

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