Part 1—You can run but you can't hide: Intrusive thoughts on six continents
Introduction
One of the key tenets of most contemporary cognitive-behavioural theories of obsessive-compulsive disorder (OCD) is that intrusive thoughts, images and impulses are normative, common – even ubiquitous occurrences experienced by individuals both with and without OCD (Bouvard and Cottraux, 1997, Clark and Purdon, 1993, Purdon and Clark, 1994, Rachman, 1997, Rachman, 1998, Salkovskis, 1985). These theories generally posit that the intrusions themselves are not problematic, but rather that the ways we react to, interpret, appraise and/or attempt to control them can cause distress, fear, guilt, avoidance, compulsions (both overt and covert), as well as a host of other symptoms including an increase in the frequency and/or duration of the intrusions themselves.
Since the 1970s, several studies have shown that unwanted, intrusive thoughts, images and impulses are experienced by the overwhelming majority of participants tested (indeed, nearly all participants in most cases reported some form of intrusion) across a number of different research sites (e.g., Purdon and Clark, 1993, Rachman and de Silva, 1978, Salkovskis and Harrison, 1984). In their landmark paper, Rachman and de Silva first distributed a questionnaire to 124 nonclinical participants (including students and hospital employees) enquiring about the presence of unacceptable thoughts or impulses. Of the 124 individuals surveyed, 99 reported the presence of such intrusions, although an additional five were reclassified as having intrusions based on their unsolicited statements about the nature of their thoughts; a total of 104 (or 84% of the sample) individuals were determined to experience unacceptable thoughts or impulses. The authors further reported that in this sample, there were no age- or sex-related differences in the experience of intrusions. The second study reported in the article employed an interview-based assessment strategy to compare the unacceptable thoughts and impulses reported by clinical vs. nonclinical participants. Impressively, the content of intrusions reported by nonclinical participants was largely indistinguishable from that reported by clinical participants. Six ‘judges’ who had experience working with ‘obsessional patients’ were asked to indicate whether the reported intrusions originated from a clinical or nonclinical individual. Results indicated that although the judges could identify many of the nonclinical intrusions reasonably well, their performance at discerning the intrusions reported by clinical participants was poor. The authors also conducted a number of comparisons between normal and abnormal intrusions in terms of frequency, distress, resistance, and other factors. Rachman and de Silva concluded that although there were important differences between normal and abnormal intrusions in terms of frequency and distress, there were important similarities in content – and crucially, that unacceptable thoughts and impulses were very common among those without a clinical problem.
Several replications of the above study have been conducted (e.g., Purdon and Clark, 1993, Salkovskis and Harrison, 1984), and generally demonstrated similar, if not higher proportions of nonclinical individuals reporting unwanted intrusions (e.g., 88.2% in the study by Salkovskis & Harrison, 1984). That said, there has been recent theoretical and empirical work which challenges the universality of unwanted intrusive thoughts, images and impulses (e.g., O'Connor, 2002). One such study (which re-evaluated the data collected by Rachman and de Silva (1978)) found that psychologists were able to distinguish between clinical and nonclinical intrusions beyond chance levels (Rassin & Muris, 2007). In a second study, Rassin, Cougle, and Muris (2007) found that while nonclinical participants endorsed intrusions, these were primarily those intrusions originating from previously tested nonclinical individuals; those participants who endorsed intrusions originating from individuals with OCD tended to have higher levels of OCD symptoms.
Despite the exceptions noted above, the generally well-replicated finding that intrusions nearly identical to those reported by individuals with OCD are also nearly universally experienced by nonclinical individuals was the foundation for the development of a theoretical understanding of the nature of intrusions in OCD. How can (almost) everyone experience unwanted intrusions, while only some develop OCD? Rachman, 1997, Rachman, 1998 suggested that “obsessions are caused by catastrophic misinterpretations of the significance of one's intrusive thoughts (images, impulses)” (Rachman, 1997, p. 793). Inspired by the misinterpretation-based theory of panic (Clark, 1986), this concise and causal theory has been the subject of great interest (e.g., Abramowitz et al., 2007, Newth and Rachman, 2001, Purdon, 2002, Rassin et al., 1999, Salkovskis et al., 2000), and has led to a cohesive and effective treatment (Rachman, 2003, Whittal et al., 2010). Indeed, two of the six initial belief domains (i.e., beliefs about the importance of and control over one's thoughts) proposed by the Obsessive Compulsive Cognitions Working Group (OCCWG, 1997) are closely associated with elements of this theory, and are often the target of both behavioural and cognitive interventions for OCD (e.g., Abramowitz, 2006a, Clark, 2004).
These and other investigations provided important empirical information about the nature of intrusions, and led many to address the question of why intrusions are only problematic for some and not for others. Responses to this question have been most fruitful, and comprise some of the most widely-used cognitive-behavioural approaches to understanding and treating obsessions and other forms of OCD. One of the limitations of this early work on obsessions was that the data were collected in a single city without regard to international or cultural differences that may influence the nature and/or number of intrusions that may be experienced and/or reported. Although some work has been done to elucidate and compare the experience of intrusions and other OCD-relevant phenomena in Italy (Sica et al., 2002a, Sica et al., 2002b), and between Italy, the United States and Greece (Sica, Taylor, Arrindell, & Sanavio, 2006), there is a clear need to test the hypothesis that unwanted intrusive thoughts, images and impulses are present and common in nonclinical populations, across cultures, around the world. This was the primary aim of the current study. A secondary aim was to assess the prevalence and nature of not only the intrusions themselves, but also of the interpretations/appraisals of and control strategies used to attempt to regulate these intrusions, as these form the core of many cognitive-behavioural theories of OCD (a cross-cultural/international examination of these appraisals is reported in Moulding et al., 2014).
In our work toward these aims, we recognised a problem in some previously-used assessment strategies employed to detect intrusions: the use of paper-and-pencil self-report measures has the capacity to capture cognitive phenomena which either are not robustly intrusive (e.g., worry, rumination) or are not distinguishable from the examples provided in the measure's instructions (a commonly reported problem with the Interpretation of Intrusions Inventory; OCCWG, 2001, OCCWG, 2003, OCCWG, 2005). Although distinguishing between intrusions, worry and rumination can be challenging (e.g., Clark and Claybourn, 1997, Langlois et al., 2000, Wahl et al., 2011, Watkins et al., 2005) we felt that the best way to ensure that our study captured unwanted intrusive thoughts (rather than worries, rumination or other cognitive phenomena) was to employ a semi-structured interview with highly-trained interviewers (see Clark and Radomsky (2014) for information about the history and development of the International Intrusive Thoughts Interview Schedule (IITIS; Research Consortium on Intrusive Fear; RCIF, 2007)).
Section snippets
Participants
Seven hundred and seventy-seven university student participants in 15 cities across 13 countries and six continents volunteered to participate in the current study. They were compensated with course credit or entry into a cash draw. The sites were located in Africa (Makeni, Sierra Leone), Asia (Herzliya, Israel; Hong Kong; Ankara, Turkey; and Tehran, Iran), Australia (Melbourne), Europe (Chambery, France; Firenze/Padova, Italy; Thessaloniki, Greece; and Valencia, Spain), North America
Participant characteristics
Mean scores on the OCI-R (M=15.80, SD=11.31) and the OBQ-44 (M=138.68, SD=39.37) corresponded with published student sample norms (Foa et al., 2002; OCCWG, 2005). Mean scores on the DASS-21 depression (M=7.78, SD=7.25), anxiety (M=6.58, SD=6.80), and stress (M=12.24, SD=8.00) subscales were slightly higher than published community norms, but well below published norms for clinical samples (Antony et al., 1998).
Demographic characteristics (age, years of education, sex, and relationship status)
Discussion
The main aims of this study were to examine, in a large international context, some of the fundamental components of cognitive theory as it applies to obsessions – namely that unwanted intrusive thoughts, images and impulses are extremely common, as are the types of appraisals and control strategies proposed to operate in OCD (e.g., Clark and Purdon, 1993, Rachman, 1997, Rachman, 1998). A failure to detect high levels of UITs in an international context (or for that matter to detect maladaptive
Acknowledgements
We are grateful to the anonymous reviewers for their helpful comments on an earlier draft of this manuscript. We are also grateful to collaborators and team members who were not able to participate in this publication (Daniel Abebe, Randy Frost, Adriana del Palacio-González, Angel Carrasco, Lisa Serravalle, Janice La Giorgia, and Jeff Renaud).
This work was supported in part by a Social Sciences and Humanities Research Council of Canada (SSHRC) International Opportunities grant to David A. Clark
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