The obsessive-compulsive disorders (OCDs) have long been derived from anxiety in the main classification systems. This tradition follows in part the early analysis of OCD and other disorders by Freud who proposed, among many other things, that consciously experienced anxiety is a consequence of the transformation of repressed libido (e.g., Breuer & Freud, 1895). Thus, the most recent American (DSM-IV) and World Health Organization (ICD-10) classification systems both include obsessive-
compulsive disorders as subtypes of anxiety disorders. For example, DSM-IV (APA, 1994) criteria for obsessions include the following:
1 Recurrent and persistent thoughts, impulses, or images that are experienced, at some time during the disturbance, as intrusive and inappropriate and that cause marked anxiety or distress.
2 The thoughts, impulses, or images are not simply excessive worries about real-life problems.
3 The person attempts to ignore or suppress such thoughts, impulses, or images, or to neutralise them with some other thought or action.
4 The person recognises that the obsessional thoughts, impulses, or images are a product of his or her own mind.
Both the general approach to classification of obsessions and compulsions and their specific defining criteria therefore emphasise an anxiety-based origin for such problems.
In contrast to the traditional and current classification systems, and in parallel to our analysis of specific phobias, we propose that certain types of OCD may be primarily derived from the basic emotion of disgust rather than the basic emotion of fear or anxiety. Although much less is known about OCD than about phobic disorders, epidemiological studies have suggested that the incidence in the community is higher than would be expected on the basis of attendance at psychiatric services. Thus, Myers et al. (1984) reported that mild obsessional problems showed a prevalence of between 1 and 2 per 100, although less than 1% of the psychiatric outpatient population present with an obsessive compulsive disorder. Even on epidemiological grounds, however, there appears to be a case to be made for two different groups of obsessional disorders. Minichiello et al. (1990) found that the onset of obsessional checking disorders tended to occur at about 18-19 years and that this group contains relatively more males than the second group of cleaning obsessionals, who have a later age of onset at about 27 years and who tend to be female. Studies of the content of obsessional disorders also suggest that there may be at least two groups (McKay et al., 2004). A study by Akhtar et al. (1975) showed that 46% of their sample reported dirt/contamination obsessions. A more recent study by van Oppen et al. (1995) of 206 obsessional patients showed that a factor-analytic derived measure of "Washing" correlated significantly with measures of depression and with interpersonal sensitivity, but did not correlate significantly with measures of anxiety or hostility. This study therefore provides good evidence that there is a subgroup of obsessional patients whose problems are not related to anxiety, but which are disgust-based.
Evidence has now begun to accumulate in favour of a role for disgust in some types of OCD following our proposal for such in the first edition of this book. Phillips et al. (2000), in an fMRI study of washer versus checker types of OCD, found specific insula activation for washer-relevant disgust pictures (e.g., urinals, rubbish bags) but both washers and checkers showed elevated insula activation for general disgust pictures (e.g., wounds, cockroaches, decaying food) compared to controls. Studies that we have already noted above in non-clinical populations have shown correlations between disgust sensitivity and obsessional symptoms especially related to washing (Mancini et al., 2001; Thorpe, Patel, & Simonds, 2003; Woody & Tolin, 2002). An fMRI
study by Shapira et al (2003) of eight OCD patients with contamination fears showed similar activation compared to healthy controls for threat (anxiety) pictures, only differing from controls for disgust pictures and again showing increased activation of the insula. Taken together, the evidence is beginning to point to a useful distinction between disgust and fear in the aetiology and maintenance of different types of OCD.
In relation to the treatment of OCD, the general two-factor theory of learning originally applied to anxiety disorders (Mowrer, 1939; see Chapter 6) was applied to obsessive-compulsive disorders by Dollard and Miller (1950). In this model, escape or avoidance from an anxiety-provoking conditioned stimulus is maintained through anxiety reduction. Rachman and Hodgson (1980) and other researchers have noted, however, that the negative emotional state in OCD is best characterised by the term "discomfort" rather than just anxiety, in that a range of unpleasant emotions may be experienced in the presence of the crucial stimulus. The main treatment method for dealing with OCD has been exposure to the avoided stimulus together with response prevention. Whereas exposure on its own may be sufficient to overcome the passive avoidance present in specific phobias, the characteristic active avoidance associated with OCD, in which the individual typically experiences an urge to carry out a compulsive action, is normally prevented during behavioural treatment of the disorder. To date, the outcome literature has shown that exposure plus response prevention is the most effective form of treatment for OCD (e.g., Eddy et al., 2004; Emmelkamp, 2004). However, it is apparent that the treatment may be more successful for those with cleaning disorders than for those with checking disorders. In an insightful analysis of this problem, Watts (1995) has suggested that in compulsive washers the contamination-anxiety may be effectively reduced by compulsive washing, whereas in compulsive checking there is less apparent anxiety reduction. In terms of treatment, therefore, Watts suggests that instead of preventing checking altogether, the checker should be allowed a single high-quality check that is carried out consciously, rather than being allowed to enter a sequence of repetitive checks that may be carried out automatically. In terms of our current analyses, however, we should emphasise that "contamination-anxiety" or "discomfort" may reflect a combination of disgust and anxiety. If true, then higher levels of depression should be reported for cleaning rather than checking disorders, if our proposal that disgust is common to some forms of OCD and depression has any validity. The treatment results may also indicate that more active avoidance strategies may be a feature of disgust-based obsessions and phobias, because of attempts to rid the body of presumed contamination, in contrast to the more passive avoidance in anxiety-based phobias in which avoidance of the object or situation (e.g., in fear of flying) is sufficient.
The probable type of onset for the two groups also tends to be different, although again the evidence is sparse. Rachman and Hodgson (1980) reported that the later onset of cleaning disorders in women tends to be sudden and is sometimes associated with pregnancy and the transition to motherhood. However, the earlier onset of checking disorders in men tends to be more gradual and to be associated with increases in responsibility in both work-related and social settings. Ware, Jain, Burgess, and Davey (1994), as we have noted above, have also found significant correlations between levels of disgust sensitivity, reported fears towards disgust-relevant animals, and the washing subscale of the Maudsley Obsessive Compulsive Inventory (MOCI). We might hypothesise therefore that cleaning disorders are more likely to arise because of disease/contamination concerns, which are of particular biological and evolutionary importance around pregnancy and childbirth. In contrast, checking disorders are more likely to reflect the anxiety-based appraisal that the individual's coping resources will be insufficient to meet increasing demands. However, we must emphasise that it would be an error to equate all cleaning disorders with disgust and all checking disorders with fear, because the symptoms merely reflect a final common pathway which could be reached by a variety of routes. Hence, a number of exceptions to these rules were noted by Rachman and Hodgson (1980), one of our own favourites being the patient who reported the gradual onset of a cleaning compulsion in relation to any word or photograph or object associated with the City of Birmingham.
In relation to current and recent theoretical models of OCD, there is little as yet that might identify two different groups of individuals. Reed's (1985) influential cognitive model focused on so-called "underinclusion" in that obsessionals were considered to pay too much attention to detail in a variety of cognitive tasks. Although some empirical support has been found for Reed's underinclusion hypothesis, there are a number of methodological and conceptual problems with the supporting studies (see Tallis, 1995). In addition, the theory is cognitive in a narrow sense, because it fails to account for the emotional and motivational features of OCD; this problem can be likened to the problems encountered by Seligman's original learned helplessness theory (1975) which, although appealing in its simplicity, unfortunately failed to account for the emotional concomitants of depression (see Chapter 4).
A potentially more promising line of theorising in work on OCD has been offered by Salkovskis (e.g., 1985) and by Rachman (e.g., 1993, 2003) in their focus on responsibility and guilt in obsessional disorders (see also Moulding & Kyrios, 2006, for related arguments concerning control). For example, Rachman (1993) has summarised four key elements that relate to the attachment of excessive significance to intrusive thoughts, images, and impulses:
1 A high level of responsibility is taken for intrusions.
2 Intrusions are given heightened significance.
3 Thoughts and actions are more likely to be fused ("the thought is the deed").
4 There may be continuous attempts to "neutralise" the intrusions, for example through the use of mental or behavioural compulsions.
Some preliminary evidence in favour of the increased responsibility hypothesis has now been reported. For example, Rheaume, Ladouceur, Freeston, and Letarte (1995) found increased ratings for both danger and responsibility in students rating scenarios relevant to OCD. Rachman (2003) has also reported that if OCD sufferers become inpatients, their symptom levels at first reduce dramatically. He suggested that this initial reduction may be due to a temporary sharing of the burden of responsibility with the ward staff. Of particular importance to us, however, is the fact that Rachman and Salkovskis have highlighted the role of responsibility and guilt; thus, we have derived the complex emotion of guilt from the basic emotion of disgust and would therefore concur with these theorists on the role of a disgust-derived emotion in OCD. However, whereas Rachman and Salkovskis have pointed to the role of guilt, in parallel to our previous analysis of depression (see Chapter 7) we would argue instead that shame as a more extreme disgust-based reaction to the self may be more appropriate. Although it can be difficult to distinguish shame and guilt with self-report measures, some evidence in favour of a shame-based rather than guilt-based analysis for obsessive-compulsive disorders has been summarised by Harder (1995). Harder found that self-report measures of shame and obsessive-compulsive problems remain significantly correlated when the effects of guilt are partialled out, but the significant correlations with guilt are no longer significant when the effects of shame are partialled out. It is possible, however, that Rachman and Salkovskis have simply used the term "guilt" in a looser sense than is defined in the emotion literature. Nevertheless, their approach suggests the possibility that disgust may play a role not only in the more obvious cleaning and washing disorders that we have focused on, but also in checking disorders because of a disgust-based reaction towards particular intrusions.
Turning briefly to studies of cognitive processes and cognitive biases in OCD, the same issues arise that we encountered earlier in our discussion of phobias; namely that although the materials used in these studies are treated as if they were anxiety-related, in fact, they are often disgust-related. For example, studies by Foa and McNally (1986), Foa, Ilai, McCarthy, Shoyer, and Murdock (1993), and Lavy, van Oppen, and van den Hout (1994) provide data on dichotic-listening and Stroop tasks (see Chapter 6) carried out with OCD patients. However, in each of the studies the researchers used a mix of anxiety-relevant and disgust-relevant materials, yet they consider their results only in relation to fear. To consider one of the studies in more detail, Foa et al. (1993) carried out a primed Stroop task in which the prime words "danger", "disturb", and "fruit" were used to prime a series of contamination, threat, and neutral words. The results reported from three groups of "washer", "nonwasher OCD", and "control" participants showed clear support for our proposals; thus, washers showed significant Stroop interference with contamination words, but not threat words, whereas nonwasher OCD participants showed Stroop interference from threat words but not from contamination words. However, the researchers were puzzled by the fact that the prime word "danger" failed to have a priming effect on contamination words for the washer OCD group. Our proposals suggest that this failure occurred because "danger" is primarily fear-related rather than disgust-related; thus, if there is an effect to be found in the Foa et al. primed Stroop task, it should occur with a disgust-derived prime such as "dirt" or "contamination" rather than with a fear-derived prime. A study by Tata, Leibowitz, Prunty, Cameron, and Pickering (1996) reported results from the dot-probe task (see Chapters 4 and 6 for details of this task) in a group of OCD patients with contamination concerns and groups of high and low trait-anxiety controls. The results showed that the OCD group were vigilant for the contamination-related words, but not for the social threat words, thereby offering further support for the proposal that at least some types of OCD may be primarily disgust-based rather than anxiety-based disorders.
To conclude, there is preliminary evidence from a number of sources that some obsessive-compulsive disorders may be primarily disgust-based rather than anxiety-based, contrary to current diagnostic and classificatory systems. Although the distinction between so-called washing and checking obsessional patients may, at least superficially, provide a possible boundary between these two varieties, in practice we suspect that the distinction will not map onto the form or content of the disorders so neatly. The recent focus on responsibility and guilt in relation to OCD seems to present a move in the right direction, although we suggest that shame rather than guilt should be the disgust-based emotion given more prominence. Even in cases that are primarily anxiety-based, however, there still appears to be a secondary role for disgust in relation to the individual's attempts to eliminate a thought, image, or impulse that is experienced as ego-alien. In the process of feeling distressed about such thoughts, images, or impulses, the individual attempts to rid the self of this unacceptable material in a manner analogous to the gut eliminating its own unacceptable contents. We suggest too that some of the empirical and experimental studies of OCD will be more readily interpretable and provide more revealing data once the distinction between disgust and anxiety is explicitly acknowledged in the design of future studies.
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