Obsessive Compulsive Disorder, (OCD), is a common anxiety disorder characterised by intrusive and uncontrollable thoughts – obsessions – coupled with the need to perform specific acts repeatedly – compulsions. Both are believed to be chronic, cause distress and/or interfere with routine, daily life (American Psychiatric Association, 2013). The obsessions and compulsions can occur separately, or more commonly, at the same time (Abramowitz, Taylor & McKay, 2009). Despite common OCD themes identified, individual presentations of this anxiety disorder vary considerably. A common clinical obsession is fear of contamination, particularly microbial infection, and obsessive doubt (Bloch et al, 2008).
Compulsions are behavioural responses developed to negate obsessions. Frequently seen compulsions are cleaning, washing and checking. For the OCD sufferer, compulsive behaviours must be performed precisely, exactly and often to prevent ‘something bad’ occurring (Szechtman & Woody, 2004). Rituals are meticulously carried out hundreds of times each day with any attempt at prevention causing extreme anxiety.
In 1979, the first cognitive behavioural formulation of obsessive neurosis was developed. Since then, there has been marked increase in interest in the role of cognitive and behavioural processes in OCD (McFall & Wollersheim, 1979). Subsequent models have attempted to explain the causation and maintenance of obsessive compulsive disorder such as Rachman & Hodgson’s (1980) Behavioural Model; Salkovskis’s (1985) Cognitive-Behavioural Model and the cognitive thought-action fusion hypothesis (TAF; Shafran & Rachman, 2004; Rachman, 1993). Despite the varied explanations for and of OCD, it is thought the most empirically supported model is the cognitive behavioural approach (Abramowitz, Taylor & McKay, 2009).
This approach suggests OCD sufferers have an inflated sense of responsibility about outcomes; distorting thought patterns and making the sufferer believe that omission to complete any of the ritualistic behaviours will cause harm to befall others or themselves (Shafran & Rachman, 2004). Sufferers can experience difficulty distinguishing between thought and action; it is believed that intrusive thoughts, potentially unacceptable and distressing, can influence events in the world – the thought-action fusion hypothesis (TAF); Rachman, 1993) – thinking about wanting someone dead will result in that person’s death.
The TAF hypothesis has been subdivided into moral TAF and likelihood TAF (Rachman, 1997). In moral TAF, the OCD sufferer may believe having intrusive thoughts makes them as guilty as if they had acted upon those thoughts. Likelihood TAF, is when the OCD sufferer believes that having thoughts about a disturbing event increases the probability of that event occurring (Wilhelm ; Steketee, 2006). Likelihood TAF, can be further divided into likelihood-self, where the adverse event affects the thinker, and likelihood-other, where the adverse event will affect another (citation needed). Both constructs have been shown to be distinct but related (Rassin, Merckelbach, Muris, ; Schmidt, 2001; Shafran ; Rachman, 2004).
The cognitive distortion of TAF forms the basis of Rachman’s (1998) misinterpretation of significance in his OCD model. Rachman (1998) suggests obsessive compulsive behaviours are the result of distorted cognitions regarding the power and significance of thoughts arguing a catastrophic misinterpretation results from seeing thoughts as “important, personally significant, revealing and threatening” (p794). Likelihood TAF supports an intrusive thought that can result in an individual feeling anxious, guilty and dangerous prompting the sufferer to suppress and negate thoughts through mental ritual or to prevent the feared event occurring through avoidance and physical compulsion (Shafran, Thordarson, & Rachman, 1996).
In performing these actions, feelings of anxiety may be immediately reduced but behaviours are negatively reinforced (Salkovskis, & Kirk, 1989). Similarly, actions are negatively reinforced when the feared event does not happen. This is supported by Carr’s (1974) research, which found after compulsive behaviour, self-reported anxiety and psychophysiological arousal reduced. As a result, TAF beliefs remain unchallenged and the individual remains hyper-vigilant to their thoughts paradoxically, increasing their frequency and threat salience. Morality TAF can result in similar feelings of anxiety and feelings of being bad or insane. Support for this approach comes from research conducted by Rachman and de Silva (1978) noting intrusive thoughts universal with little difference in content reported by OCD sufferers and those without a mental health diagnosis. Rachman (1998) proposed, that, if we interpret thoughts, images or impulses to hold meaning or power then these normal intrusions can become obsessions. Subsequent anxiety results in efforts to control these intrusions, which can result in more intrusions and escalating distress (Wegner, Schneider, Carter, ; White, 1987).
Cognitive hypotheses of OCD such as those of Rachman, 1998 and Salkovskis, 1999, determine TAF relevant to the development and maintenance of obsessional problems for two reasons. Firstly, if OCD sufferers believe their negative thoughts are the moral equivalent of actions they will experience extreme distress. Secondly, should OCD sufferers believe thinking such thoughts increases the likelihood of an unwanted event, potentially, they may engage in behaviours designed to negate the thought or prevent the occurrence of disastrous consequences. Studies consistent with this theoretical account have repeatedly established a relationship between TAF and OCD symptoms with stronger correlations for likelihood TAF than moral TAF (Amir et al., 2001; Rassin et al, 2001; Shafran et al., 1996).
Salkovskis, viewed TAF a specific example of inflated responsibility for harm, proposing if an OCD sufferer believes their thoughts could cause an adverse event they are likely to experience an inflated responsibility and act to prevent the event (Shafran, et al., 1996). In 2000, Salkovskis and colleagues determined OCD adults had increased levels of inflated responsibility compared to those with other anxiety disorders. Rhéaume, Freeston, Dugas, Letarte and Ladouceur (1995) established measures of responsibility accounted for up to 37.7% of variance in obsessive compulsive symptoms in a large student sample. Bouchard, Rhéaume and Ladouceur (1999) found a non-clinical sample of 51 adults showed more hesitational and checking behaviours in a high responsibility sorting task than in a low responsibility sorting task. These findings indicate a link between TAF and OCD, with the group design providing strong evidence of a causal relationship between responsibility and compulsive symptoms only, not for obsessive symptoms.
Further support for the role of TAF in OCD comes from research questionnaire by Amir and colleagues (2001) to measure TAF – their findings confirmed obsessives scored higher than non-obsessives. Individuals exhibiting OC symptoms rated higher against the likelihood of negative events happening due to negative thinking (Shafran, Thordarson, ; Rachman, 1996) also rating highly against the likelihood they would prevent harm by positive thinking compared to individuals without OC symptoms. These results suggest the role of thought–action-fusion in OCs may extend to exaggerated beliefs about power of thought.
TAF is associated with tendencies towards OCD and may contribute to its symptoms. However, literature investigating TAF and other variables implicated in OCD remains inconclusive. It is suggested TAF is not OCD specific but also prevalent in other disorders (Berle ; Starcevic, 2005) like panic disorder, social phobia, generalised anxiety disorder and eating disorders (Abramowitz, et al., 2003; Rassin, Diepstraten, et al., 2001). Because of this, it is suggested TAF may be a pervasive bias associated with psychopathology rather than OCD specific (Berle ; Starcevic, 2005). Coles, Mennin and Heimberg (2001) found obsessive features and worry distinguishable by the construct of TAF. However, this study was limited to a non-clinical student sample and it is possible TAF is more highly correlated with worry in clinical samples. The relationship between TAF-morality and obsessive compulsive symptoms is less well established than that of the relationship between TAF-likelihood and OCD.
The cognitive-behavioural approach to the TAF hypothesis concentrates on internal cognitions together with the role of learning as explanations for OCD whilst ignoring other potentially major contributory factors to OCD symptoms such as genetic/neural factors as suggested by the biological approach. It can, therefore, be viewed as a reductionist approach although being combined with behavioural strategies improves this somewhat.
The biological approach suggests genetics and neural factors such as brain structure and an imbalance in neurotransmitters, cause OCD. Genetic research identified two specific genes (citation needed); the COMT gene is linked to the production and regulation of the neurotransmitter, dopamine. One variation of the COMT gene, causes higher levels of dopamine, a variation common with OCD sufferers compared to non-sufferers. It is also associated with some of the compulsive behaviour OCD symptoms (citation needed). The SERT gene, also known as 5-HTT gene, is linked to the neurotransmitter serotonin affecting its transport and lowering levels of the chemical which are associated with OCD and depression (citation needed).
Neural explanations suggest specific areas of the brain are linked to OCD; the orbitofrontal cortex (OFC) and the thalamus (citation needed). The OFC converts sensory information into thought and action; is involved in decision making; anxiety about social and other behaviours. Functions of the thalamus include controlling checking and other safety behaviours (citation needed). In OCD, the OFC and thalamus are believed to be overactive (citation needed); over activity in the thalamus results in increased motivation to clean, check for safety and overactivity in the OFC increases anxiety and planning to avoid anxiety. One suggestion is that the heightened activity in the orbitofrontal cortex not only increases the conversion of sensory information to actions (behaviours) prompting compulsions (citation needed) but prevents sufferers patients from stopping their behaviours. This is supported by research using PET scans, which have found higher activity in the orbitofrontal cortex in patients with OCD (citation needed).
Support for the role of genetics in the causation of OCD comes from family studies such as Lewis’ (1936) who examined patients with OCD and found that 37% of the patients with OCD had parents with the disorder and 21% had siblings who suffered, supporting the theory of a genetic influence for OCD. Further support for the biological explanation of OCD comes from studies of twins which provided strong evidence for a genetic link. Nestadt et al. (2010) conducted a review of such studies examining OCD finding 68% of identical twins and 31% of non-identical twins had OCD. Aligning with Carey and Gottesman’s (1981) findings where identical twins showed a concordance rate of 87% for obsessive symptoms and features compared to 47% in fraternal twins. However, no twin study has yet found a concordance rate of 100% in identical twins meaning there must be other contributory factors overlooked in the biological approach.
Because not all with OCD have the same structural brain abnormalities, so study findings cannot be generalised across the whole population emphasising the need for further research to determine other factors that may be responsible for OCD.
In conclusion, evidence suggests the cognitive-behavioural approach to the TAF hypothesis is linked with OCD but there are other influential factors that remain unexplained. Further research combining these factors are required using the bio-psycho-social approach such as the diathesis–stress model(citation needed) which offers a more comprehensive account of OCD causes as it combines the influence of nature (genetic predisposition, personality) and nurture (conditioning, social learning, and stress) and individual differences would be valuable.