Is Obsessive-Compulsive Disorder a Disturbance of Security Motivation?

Is Obsessive-Compulsive Disorder a Disturbance of Security Motivation? Comment on Szechtman and Woody (2004)
[COMMENT]
Taylor, Steven1,4; McKay, Dean2; Abramowitz, Jonathan S.3
1Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada
2Department of Psychology, Fordham University
3Department of Psychiatry and Psychology, Mayo Clinic, Rochester, Minnesota.
4Correspondence concerning this article should be addressed to Steven Taylor, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, British Columbia, V6T 2A1, Canada. E-mail: taylor@unixg.ubc.ca
We thank Henry Szechtman, Erik Woody, W. Jake Jacobs, Gail Steketee, Randy Frost, and Richard J. McNally for their comments.
Received Date: March 8, 2004; Revised Date: August 2, 2004; Accepted Date: November 3, 2004
Abstract
H. Szechtman and E. Woody (2004) proposed that obsessive-compulsive disorder (OCD) is caused by a malfunctioning brain security motivation system. In the current article, the authors' review of the model suggests that it is limited in the following ways: (a) It is built on a selective review of the empirical literature,建立在有選擇性的實徵文獻回顧上 (b) it offers no explanation for many important OCD phenomena未能解釋許多OCD的重要現象, (c) it fails to distinguish OCD from generalized anxiety disorder,不能有效區辨OCD與其他的焦慮性疾患 (d) some of the model's predictions are ambiguous or unfalsifiable, 有些預測變項定義模糊不清and (e) other predictions are refuted by previously published research有些預測變項已被先前的研究反駁了. Models proposing that OCD is caused by a single dysfunctional mechanism, such as the security motivation model, have difficulty explaining the complexity and heterogeneity of OCD.
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Many different models have been proposed to explain obsessive-compulsive disorder (OCD; e.g., see Clark, 2004; Jakes, 1996; Salkovskis, 1996). There is no leading model, and new conceptualizations continue to appear in the literature. A good model should be able to do several things (cf. Jakes, 1996; Lakatos & Musgrave, 1970; Meehl, 1990). It should be able to account for both the processes and the contents of the disorder.1 This includes an explanation of the major clinical characteristics of OCD (obsessions, compulsions, and their interrelations) and the mechanisms underlying these features. As part of this, a good model should be able to explain the symptom heterogeneity of OCD. For example, why do some people have checking compulsions while others have contamination obsessions and still others have hoarding rituals?
A good model of OCD should not fall prey to the problem of overinclusiveness in its explanation of clinical features. Obsessive-compulsive (OC) symptoms are empirically distinguishable from symptoms of other disorders, such as pathological worry in generalized anxiety disorder (GAD; Brown, Antony, & Barlow, 1992; Brown, Moras, Zinbarg, & Barlow, 1993; and see Clark, 2004, for a review). Accordingly, a model of OCD should specify mechanisms that are specific to OC symptoms. A model composed of nonspecific mechanisms fails to explain why a person develops OCD instead of some other disorder.
A good model of OCD should also be clear in its predictions. There should be no ambiguity about what counts as evidence for or against the model. The model should also lead to predictions that are falsifiable. Falsification contributes to scientific progress by enabling researchers to compare competing models in terms of whether their predictions are empirically supported (Lakatos & Musgrave, 1970). Predictions derived from a model of OCD should also be consistent with what is already known about the disorder; the predictions should not be refuted by preexisting evidence.
Finally, a good model should have treatment relevance. OCD is a common and often chronic and disabling disorder (American Psychiatric Association, 2000). A useful model of OCD should enhance the understanding of current treatments and should suggest new ways of improving treatment outcomes. It should be able to help make sense of why some treatments are effective (e.g., cognitive restructuring), why other treatments are largely ineffective (e.g., relaxation training), and why some OC symptoms (e.g., hoarding) are more difficult to treat than other symptoms (e.g., checking and washing; Abramowitz, Franklin, Schwartz, & Furr, 2003; Clark, 2004; Steketee & Frost, 2003).
In an effort to explain the contents (symptoms) and processes of OCD, Szechtman and Woody (2004) recently proposed that the core problem causing OCD is a malfunctioning security motivation system in the brain. The model states that security motivation is a set of biologically based (hardwired) behaviors that serve to protect the self or others from danger. Security-related activity includes checking for potential threats. According to the model, security-motivated activities are terminated by a “feeling of knowing” called yedasentience. For example, the feeling that a door is properly locked purportedly terminates door checking. The model states that when the security motivation system is dysfunctional, the person fails to reach a state of yedasentience and thereby continues to engage in security-seeking behaviors such as repeated checking. Our purpose in the present commentary is to evaluate Szechtman and Woody's model in light of the desiderata for a good model of OCD and to suggest some promising directions for further research into this complex disorder.
Explaining the Major Clinical Characteristics of OCD
Obsessions, Compulsions, and Their Interrelations
Szechtman and Woody's (2004) model “focuses largely on compulsive behavior” (p. 122), which they regard as the most important feature of OCD in need of explanation. To justify their assumption about the importance of compulsions, Szechtman and Woody stated that 51% of OCD patients “have compulsions without obsessional thoughts (Rachman & Shafran, 1998; Rasmussen & Eisen, 1991)” (p. 112). This statement does not accurately reflect the original sources and no doubt is an inadvertent error. Rachman and Shafran (1998) reported that 6% of patients have compulsions without obsessions. Rasmussen and Eisen (1991) stated that “most patients presented with multiple obsessions and compulsions and that the frequency of patients with only obsessions or compulsions was low” (pp. 17–18). Szechtman and Woody's claim is also inconsistent with findings from other studies. For example, Rasmussen and Tsuang (1996) found that 2% of OCD patients had compulsions in the absence of obsessions. In the Diagnostic and Statistical Manual of Mental Disorders (4th ed.) field trial for OCD, only 1.7% of over 450 OCD patients had compulsions without obsessions (Foa & Kozak, 1995).
Szechtman and Woody's (2004) conceptual emphasis on compulsions is also inconsistent with one of the earliest (e.g., Roper, Rachman, & Hodgson, 1973) and most consistent experimental findings regarding the nature of OCD: that compulsions are typically the result of—that is, evoked by—obsessions (American Psychiatric Association, 2000; Clark, 2004; Ladouceur, Rheaume, & Aublet, 1997; Lopatka & Rachman, 1995; Rachman & Hodgson, 1980). Research also shows that overt compulsions are just one of many different responses to obsessions. Others include mental rituals (e.g., thinking a “good” thought to counter a “bad” [obsessional] thought), neutralization, and the concealment of obsessions (Freeston & Ladouceur, 1997). Szechtman and Woody have focused their model on symptoms (compulsions) that are a result of a more fundamental problem (obsessions).
Szechtman and Woody (2004) claimed that in OCD, “the key problem is one of stopping” (p. 112). OCD is said to arise primarily from a deficit in a stopping mechanism involving the failure to attain a state of yedasentience. To support their argument, Szechtman and Woody stated that compulsions are low in frequency but long in duration: “Most patients engage in few but extended bouts of compulsive behavior during the day” (p. 112). This claim lacks empirical support and does not consider the evidence to the contrary. Studies have shown that the frequency and duration of compulsions are highly variable both within and between people with OCD, to the point that no general claims about typical duration or frequency can be made (Marks, 1987; Rachman & Shafran, 1998; Yaryura-Tobias & Neziroglu, 1997). For example, Yaryura-Tobias and Neziroglu (1997), reported that compulsions may be brief actions or elaborate sequences of behavior, all intended to reduce obsessions.
With its emphasis on stopping mechanisms, Szechtman and Woody's (2004) model does not consider evidence indicating that the problem with obsessions and compulsions in OCD is that they are too readily started (e.g., Lee & Kwon, 2003). The sight of kitchen knives, for example, too readily triggers harming obsessions (e.g., the image of stabbing one's child) along with checking compulsions (“Is my child safe? I had better check”) in people with OCD. People without OCD may have obsessions and compulsions, but these episodes are less frequent and less often triggered by threat-related stimuli than those in people with OCD (Calamari & Janeck, 1998; Rachman & de Silva, 1978; Salkovskis & Harrison, 1984).
In summary, the emphasis on compulsions, the lack of attention to the causes of obsessions, and the lack of attention to the causal links between obsessions and compulsions are important limitations of Szechtman and Woody's (2004) model. The model also offers no explanation about why episodes of obsessions and compulsions naturally come to an end. For example, by what mechanism does a person with OCD naturally end a period of door-lock checking? Thus, the model is based on a conceptualization of OCD that is incomplete and in many ways inconsistent with the findings of clinical research.
Symptom Heterogeneity
Epidemiologic research and factor analytic studies show that OCD is a symptomatically heterogeneous condition (McKay et al., 2004). The major dimensions of OC symptoms are (a) obsessions (aggressive, sexual, religious, or somatic) and checking compulsions; (b) symmetry obsessions and ordering, counting, and repeating compulsions; (c) contamination obsessions and cleaning compulsions; and (d) hoarding obsessions and collecting compulsions (Taylor, in press). A good model of OCD should be able to explain why one person has hoarding obsessions while another person has cleaning rituals and still another has a multitude of different types of rituals. Szechtman and Woody's (2004) model, which purports to account for OCD in general rather than some particular subtype of the disorder, is silent on this important issue, just as their conceptualization offers no explanation for why obsessions and compulsions take the bizarre forms that they often do. For example, why is one OCD sufferer plagued by intrusive, distressing images of Christ on the cross with an erection while another OCD sufferer is tormented by the theme song to The Flintstones continuously running through her mind while yet another is obsessed with urges to collect used paper plates and old milk containers? (For further examples of the heterogeneous and often bizarre nature of OC symptoms, see Clark, 2004; Marks, 1987; Rachman & Hodgson, 1980; Steketee & Frost, 2003).
Distinguishing Obsessions From Worry
A good model of OCD should be able to explain why a putative dysfunctional mechanism gives rise to OCD instead of some other disorder. The security motivation model does not distinguish OCD from GAD. That is, it does not explain why the putative dysfunction would lead a person to develop OCD instead of GAD. The latter is characterized by persistent, uncontrollable worry (American Psychiatric Association, 2000). Szechtman and Woody (2004) stated that a dysfunction in the security motivation stopping mechanism gives rise to OCD, whereas dysfunction in the start (trigger) mechanism gives rise to GAD. There are two problems with this formulation. First, as we mentioned earlier, evidence indicates that OCD is associated with problems in a starting (triggering) mechanism. Second, GAD is characterized by uncontrollable worry; a person with this disorder might intentionally initiate an episode of worry but then have difficulty bringing the worry to an end (Craske, Rapee, Jackel, & Barlow, 1989; Gladstone & Parker, 2003). Thus, worry in GAD appears to be a problem of stopping (Szabo & Lovibond, 2002). Although GAD and OCD can be readily distinguished on clinical grounds (Brown et al., 1993)—just as worry and obsessions can be phenomenologically distinguished (Turner, Beidel, & Stanley, 1992; Wells & Morrison, 1994)—the security motivation model does not distinguish between GAD and OCD or between worry and obsessions.
Evaluating the Propositions and Predictions of the Security Motivation Model
Problems in Falsifiability
Szechtman and Woody (2004) stated that their model would be clearly refuted if it was shown that there is no encapsulated security motivation system. This claim encounters the problem of proving that something does not exist. A model stated in such terms is unfalsifiable because the absence of supporting evidence is not equivalent to evidence of absence. A series of experiments might fail to identify an encapsulated security motivation system, yet such findings would not clearly refute the model because they would not rule out the possibility that the security motivation system exists but the experiments failed to find it.
Conceptual Ambiguity
A model is not testable unless its basic assumptions are unambiguously stated in a manner that leads to clear predictions. As a rationale for proposing their security motivation model, Szechtman and Woody (2004) asserted that “clearly, OCD is a stark demonstration that normal control of behavior can be overridden by some powerful noncognitive-based system(s)” (p. 112). This assumes what remains to be proved. They claimed that OCD arises from a “core deficit to a noncognitive process” (p. 113), and yet their use of the terms cognitive and noncognitive is vague. Szechtman and Woody referred to “the cognitive framework” (p. 113), but there is no single or unifying cognitive framework for understanding OCD. In referring to cognition, Szechtman and Woody seem to be concerned with the cognitive contents of consciousness (beliefs, conscious perceptions). There are many other forms of cognition, such as nonconscious cognitive contents, processes, and structures (Kihlstrom, 1987).
Their use of the concept of emotion is also vague. The security motivation system is said to be a noncognitive, emotion-based mechanism. This incorrectly assumes that cognition and emotion are distinct entities and neglects evidence that emotion can be decomposed into cognitive, physiological, and behavioral components (Barlow, 2001; Davis & Lang, 2003; Foa & Kozak, 1986). The conceptual foundations of the security motivation model could be improved by disambiguating its use of concepts like cognition and emotion. In the model's current form, the distinction between cognitive versus noncognitive/emotion-based mechanisms is so ambiguous that it is untestable.
What Counts as Evidence For or Against the Model?
The model contains ambiguities concerning what counts as supporting or refuting evidence. To illustrate, consider the following claim made by Szechtman and Woody (2004), which is presented as support for their model: “No one obsesses about the possibility of making someone happy” (p. 122). Presumably this suggests that making someone happy falls outside of the domain of security motivation. But it could be argued that the happiness of others is central to security motivation: Keeping one's conspecifics in good humor is an excellent way of warding off danger. Given the widespread problem of familial and other forms of interpersonal violence, the happiness of others can be highly relevant to one's security. The fact that “no one obsesses about the possibility of making someone happy” would seem to refute rather than support the model.
Ambiguity about what counts as supporting evidence occurs elsewhere in their model. Szechtman and Woody (2004) claimed that their model would be supported by evidence showing that people with OCD, compared with controls, have a problem in stopping or satiation rather than initial sensitivity or motivation: “They should not work harder for access to the relevant security-related stimuli (e.g., water for washing and access for checking)” (p. 123, emphasis added). This prediction already seems to be refuted by the very nature of OCD; patients with washing compulsions, for example, do go to great lengths to ensure the safety of themselves or others (e.g., elaborate avoidance of public restrooms, using strong disinfectants, elaborate “decontamination” rituals that they perform when they return home). Similarly, checkers often go to great lengths to pursue their rituals (e.g., returning several times to a store to check that they have not harmed the clerk or returning home from miles away to recheck the door locks). Many published works on OCD readily illustrate the lengths to which many people with OCD go to complete their compulsions (e.g., Clark, 2004; Rachman & Hodgson, 1980). But are these really instances of working harder, or do they reflect dysfunctions in initial sensitivity or motivation? Thus, the prediction from the security motivation model is ambiguous.
Ad Hoc Explanations
The model's greatest ambiguity concerns the question of what counts as security-motivated behavior. Some OC symptoms, such as checking compulsions, appear to be security-related, but the security relevance of many other obsessions and compulsions is unclear. Consider, for example, compulsive hoarding. Humans spend millions of dollars each year trying to secure their property. But that is quite different from the activities of compulsive hoarders. People with this disorder may collect any or all of a variety of worthless objects, including flyers from department stores, old newspapers, empty milk containers, bodily secretions (e.g., urine, feces), and worthless trinkets (e.g., key chains). Is hoarding a security-procuring activity? One might devise an ad hoc argument that the collecting of some of these objects might be somehow security-related (i.e., the hoarding is motivated by fear for the consequences of losing possession of the objects; Steketee & Frost, 2003). However, it is unclear how one could claim that collecting trash and worthless trinkets is security related. Other explanations seem more plausible, such as cognitive deficits. Evidence shows that hoarders experience difficulties in making decisions, regardless of whether the decisions are relevant to security motivation (Steketee & Frost, 2003). This suggests that there is more to hoarding than problems in security motivation.
Szechtman and Woody (2004) offered no explanation for superstitious or magical rituals, which are common in OCD (e.g., Tolin, Abramowitz, Kozak, & Foa, 2001). Almost all the illustrations of the workings of their model concern compulsive checking. Szechtman and Woody did offer two ad hoc explanations for other compulsions—symmetry/ordering rituals and counting compulsions 2—although they presented no evidence to support their claims. The reliance on ad hoc explanations undermines the predictive value of their model. Reliance on ad hoc explanations also renders the model unfalsifiable (Lakatos & Musgrave, 1970): If all behaviors are potentially security motivated, then there is no way of testing the notion that compulsions arise from a deficit in security motivation, nor is there any way to determine how the deficit leads to specific symptoms in some individuals and entirely different symptoms in others.
Predictions Regarding the Specificity of Dysfunction
Szechtman and Woody (2004) stated that the locus of dysfunction in OCD is not some generalized brain dysfunction but rather a highly specific system responsible for security motivation. The model therefore predicts that OCD is characterized by deficits specific to the processing of security-related information. Neuropsychological and information-processing studies do not support this prediction. There is evidence that people with OCD, compared with controls, have deficits or abnormalities on a range of tasks, including tasks that are seemingly unrelated to issues of security. This has been shown for tasks of inductive reasoning (Pelissier & O'Connor, 2002), executive functioning and some forms of learning and memory (Greisberg & McKay, 2003), and memory confidence (Tolin, Abramowitz, Brigidi, et al., 2001). People with OCD, compared with controls, also show weakened cognitive inhibition (i.e., a weakened ability to inhibit responses, even affectively neutral responses; Enright & Beech, 1990, 1993a, 1993b; Enright, Beech, & Claridge, 1995), as indicated by negative priming tasks (Tipper, 1985). People with OCD, compared with controls, are more likely to suffer from impulse-control disorders (e.g., trichotillomania, kleptomania, pathological gambling; Frost, Meagher, & Riskind, 2001; Hollander & Wong, 2000; Swedo, 1993). In contrast to the view that people with OCD are excessively motivated to seek security, the research shows that these people are more likely (compared with normal controls) to engage in reckless or risky behaviors (e.g., kleptomania). The evidence that OCD is characterized by a wide range of deficits and other problems is not predicted by the security motivation model. Such findings suggest that OCD is associated with an array of dysfunctional mechanisms rather than arising from a sole deficit in security motivation.
Treatment Relevance
Does the security motivation model enhance the understanding of the treatment of OCD, and is the model consistent with what is currently known about the efficacy of available interventions? The most widely used, empirically supported treatments for OCD are cognitive-behavioral interventions (e.g., cognitive therapy, exposure and response prevention) and serotonergic medications (e.g., selective serotonin reuptake inhibitors; Clark, 2004; Swinson, Antony, Rachman, & Richter, 1998). Szechtman and Woody (2004) derived from their model a number of treatment-relevant predictions and claims. These authors implicated the serotonergic system in the functioning of the security motivation system and noted that this is consistent with the beneficial effects of serotonin reuptake inhibitors in OCD. However, the model does not explain why these medications are effective only for some forms of OCD (e.g., checking) and not for others (e.g., hoarding; Steketee & Frost, 2003). If serotonergic medications rectify a dysfunctional security motivation system but fail to reduce OCD (e.g., in the case of hoarding), then this should challenge Szechtman and Woody's model.
The model does not explain why cognitive therapy would be an effective treatment for OCD. Indeed, the model incorrectly implies that cognitive interventions should be ineffective: “Problems in thought cannot be readily corrected through more thought (higher cognitive processes), even with great effort. This is because, in the terminology of the present model, yedasentience is not an output of volitionally directed higher cognition” (Szechtman & Woody, 2004, p. 122).
Cognitive therapy is designed to correct problems in thought through the use of more thought. For example, patients are encouraged to examine their beliefs about the meaning of intrusive thoughts. This therapy focuses on higher cognitive processes, not on a putative noncognitive/emotion-based mechanism underlying yedasentience. Randomized, controlled studies have shown that cognitive therapy (without exposure or response prevention or other behavioral exercises) is an effective treatment for OCD (for reviews, see Clark, 2004; Swinson et al., 1998). In other words, contrary to the security motivation model, “problems in thought” can be readily corrected through more thought (higher cognitive processes).
With regard to another empirically supported treatment for OCD—exposure and response prevention—Szechtman and Woody (2004) claimed that this treatment somehow reduces the sensitivity of the security motivation system. They further claimed that after successful exposure therapy, the former OCD patient may have “a subnormal threshold of response to certain cues of potential danger, because his or her original condition was one of underactive stopping rather than overactive starting” (p. 123). Thus, Szechtman and Woody predicted that the reduction in OCD should be associated with an increase in risk taking or disregard for signs of danger. We could find no evidence to support this claim either in our own treatment studies (Abramowitz et al., 2003; McLean et al., 2001; Taylor et al., 2003) or in the treatment research literature in general, and no evidence was offered by Szechtman and Woody.
A Security Motivation Account for Compulsive Checking?
OCD is a heterogeneous disorder, and the evidence for OC subtypes suggests that there may be different pathways or mechanisms that could give rise to this disorder (or group of disorders). Although the security motivation model has difficulty accounting for many types of obsessions and compulsions, it appears to be particularly suited for explaining compulsive checking; persistent doubts about the safety of oneself and others would logically lead to persistent checking. This may be why almost all of Szechtman and Woody's (2004) examples of the workings of their model concern checking.
The model, as an explanation of compulsive checking, could be strengthened in several ways, as discussed earlier in this article (e.g., problems with unfalsifiability and conceptual ambiguity could be addressed). The model could be further strengthened by considering the recent clinical-experimental literature on OCD. There is evidence, for example, that checking actually increases doubt and uncertainty (van den Hout & Kindt, 2003a, 2003b). This suggests that a positive feedback loop may occur in OCD: Failure to achieve yedasentience may lead to more checking, which then leads to more doubting (due to increasing memory interference, e.g., “Am I recalling the most recent time I checked or a previous time?”) and thereby to even more checking. The model also could be strengthened by specifying the conditions that lead to the cessation of checking under these circumstances. Some people with OCD cease checking because of physical exhaustion or interruption by other people, but many people with OCD stop before that point. This is because they have developed elaborate rules or cognitive governance strategies over their rituals (e.g., as one patient reported, “Three strikes and you are out; that means that three checks that the door is locked means that it is safe to leave”), which terminate episodes of checking (for further examples, see Clark, 2004; Rachman & Hodgson, 1980).
Conclusions and Future Directions
Given the complexity and heterogeneity of OCD, it is not surprising that a unifying model—that is, a model such as the security motivation model, which attributes OCD in all its diverse forms to a single dysfunctional mechanism—has difficulty explaining many aspects and types of OC phenomena. In this sense, the security model is underinclusive; it treats various types of obsessions and compulsions as if they arise from a single mechanism despite the evidence to the contrary. In other respects, the model is overinclusive by proposing a mechanism that does not distinguish between two distinguishable disorders (OCD and GAD). It also does not explain why a deficit in the feeling of knowing would lead to washing compulsions in some people, hoarding in other people, and checking in still others. Some predictions from the model are ambiguous or otherwise unfalsifiable, while other predictions are refuted by the existing empirical literature.
At the outset of this article, we observed that there are many different models of OCD and that no model is currently regarded as a leading contender for explaining this complex disorder or group of disorders. Many of these models have been developed in isolation of one another, with each focusing on some particular aspect of OCD or level of analysis. Some models have been derived from ethological perspectives, whereby compulsions such as grooming rituals are seen as readily triggered fixed action patterns. A host of neurobiological models have been proposed, postulating various kinds of dysregulated brain circuitry (e.g., frontal-basal ganglia circuits) arising from various sources (e.g., genetic factors or various types of childhood infections). Other models consist of the many different kinds of cognitive-behavioral approaches. Some of the latter propose that OCD arises from particular forms of mal-learning (e.g., learning to take excessive responsibility for preventing harm), whereas other models emphasize dysfunctional information-processing styles. Added to this array of conceptual perspectives is the security motivation model.
Progress in understanding OCD could come in a variety of ways. The various models could compete against one another, pitting their track records of empirical support and refutation until a clear winner emerges. Obsessions and compulsions, in their various forms, have been recognized for several hundred years (e.g., Burton, 1652; Esquirol, 1838) and have been the subject of intense empirical scrutiny for many decades. Despite this intensive, prolonged study, a dominant model of OCD has yet to emerge. The continued competition of models may not be the best way of understanding this disorder. A more productive approach might be to consider the evidence for subtypes of OCD (McKay et al., 2004; Taylor, in press) and to explore the possibility that different models might fully or partially explain different subtypes of OCD. A noncognitive/emotion-based model such as the security motivation model may be a promising candidate for some forms of OCD (e.g., some forms of compulsive checking), whereas other models may be better suited for other subtypes of OCD. Consistent with this possibility, we recently found that some people with OCD have clinically elevated scores on measures of OC-related dysfunctional beliefs (e.g., beliefs about perfectionism and inflated responsibility), whereas other people with OCD have essentially normal scores on these measures (Taylor et al., in press). The latter group, which included compulsive checkers, might have the sort of security motivation deficit postulated by Szechtman and Woody (2004). Further studies of OCD subtypes may eventually lead to a better understanding of this etiologically heterogeneous disorder.
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1Conceivably, a model of OCD might focus exclusively on the processes of OCD, without considering specific contents. The problem with a purely process-based approach is that such a model would be unable to answer key questions concerning OCD: Why does a person develop particular obsessions and compulsions, and why does the person have these symptoms and not others? Research indicates that process and content are closely related in OCD and that obsessions and compulsions, compared with other psychopathologic phenomena (e.g., excessive worry), are characterized by distinctive processes and contents (Clark & Claybourn, 1997; Frost & Steketee, 2002). Szechtman and Woody's (2004) model strives to explain the processes of OCD, along with the development of specific contents (e.g., checking compulsions, symmetry rituals). [Context Link]
2For example, counting compulsions are said to help the person detect deviations in the environment, thereby facilitating checks for changes that may signal potential danger. It is unclear, however, how this accounts for counting in OCD, because many of the things counted by people with these compulsions have nothing to do with safety or danger (e.g., counting the number of books containing the letter K in their titles on a bookshelf, the number of purple cars on the street, or the number of syllables one hears during conversations with others). [Context Link]
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