30 COGNITIVE THERAPY IN CLINICAL PRACTICE

relationship between cognitive and behavioural treatments. The assessment and treatment techniques which are based on the cognitive-behavioural hypothesis are discussed and illustrated by clinical examples.

The behavioural model

The behavioural model of obsessive-compulsive disorder proposes that the occurrence of compulsive behaviour serves to maintain obsessional problems. The main points of the behavioural model are detailed in Table 3.1 below:

Table 3.1 Behavioural model of obsessive-compulsive disorder

(1)Obsessions are conditioned stimuli It is assumed that obsessions are conditioned anxiety stimuli which have been resistant to extinction (habituation).

(2)Anxiety relief reinforces compulsive behaviour Behaviours which terminate the anxiety or discomfort associated with obsessional thoughts are reinforced by the reduction of discomfort, so that these behaviours become increasingly likely to follow obsessions.

(3)Avoidance behaviours There are a range of behaviours which are developed over a longer period, and which have the effect of reducing the occurrence of obsessional thoughts; where extensive, these avoidance behaviours can resemble that observed in agoraphobia.

Practical implications Avoidance behaviours prevent and compulsive behaviours terminate exposure to feared stimuli, producing shortterm relief of anxiety but preventing exposure and extinction of anxiety.

It is evident from this outline of the model that there are two principal ways in which compulsive behaviour could maintain obsessional problems. Reduction in anxiety which follows the performance of obsessional rituals may reinforce the obsession, and the occurrence of compulsive behaviour serves to terminate exposure to the obsessional thought and thereby prevents habituation.

Cognitive hypotheses of obsessive-compulsive disorder

There are two principal ways in which a cognitive formulation could be applied to obsessive-compulsive disorder: either as an alternative explanation of the existing behavioural paradigm, or as a more comprehensive view which encompasses and expands the behavioural model. The first of these is similar to the cognitive explanation of other behavioural procedures in the treatment of anxiety; it could be said that obsessional behaviour maintains fears by preventing reappraisal from taking place. An example is the patient who was upset by the thought that he might harm his children through contamination unless he washes his hands in a particular way. He washes, experiences considerable relief, and his children do not come to harm. This experience is repeated many times, and he concludes that he has been successful in protecting his children from harm. Thus, the washing prevents him from discovering the true facts: only by being exposed to contamination and not washing will he discover that his fears are groundless. Note that this formulation leads to conclusions which are mostly identical to those of the behavioural model. The principal addition to existing techniques is to be found in the way that this view predicts that exposure would be most effective when it has the greatest information value, i.e. it is carried out in a way which maximises information which is inconsistent with feared disasters. An example of exposure used in this way is outlined on pp. 69–70.

This slight extension of the behavioural model, whilst having the advantage of simplicity, does not fully rescue the older behavioural model from the problems which are revealed by research findings. For instance, there is evidence in some patients that anxiety can increase as a consequence of obsessional thoughts (Beech and Liddell 1974). Discomfort evoked by obsessional stimuli is substantially reduced by the presence of the therapist in patients with checking rituals but not in patients with contamination and washing rituals (Rachman et al. 1976; Roper and Rachman 1975; Roper et al. 1973). The inability of the behavioural model to account fully for the phenomenology of obsessive-compulsive disorder and the limitations of the therapeutic applications of behaviour therapy described earlier in this chapter highlighted the need for a cognitive hypothesis on which treatment of obsessions could be based (Salkovskis 1985).

The cognitive hypothesis of obsessions proposes that intrusive thoughts are a normal phenomenon (Rachman and de Silva 1978; Salkovskis and Harrison 1984). Intrusive thoughts do not automatically have affective connotations, but acquire emotional properties as a result of appraisal. That is, intrusive thoughts can take positive, negative, or neutral affect depending on the evaluation made by the individual experiencing them (Salkovskis 1985). Intrusive thoughts are adaptive and functional in that they are crucial to a variety of human activities, including creativity and problem solving. Intrusive thoughts persist to the extent to which they have implications for intentional behaviour on the part of the person experiencing them (Salkovskis 1985, 1988). If an intrusive thought has no implications for further deliberate thought and/or action (such as mental problem solving) it will not persist. On the other hand, if an intrusive thought does have implications for intentional behaviour, then further processing will take place. A cognitive system which works in this way has several advantages; in particular, it allows

OBSESSIONS AND COMPULSIONS 31

Figure 3.1 Cognitive-behavioural model of the development of obsessive-compulsive disorder

the selection of important ideas from the welter of cognitive activity, and ensures that ideas most relevant to current concerns (positive or negative) will persist.

The cognitive hypothesis of the development of obsessional disorders

A more unfortunate implication is that particular types of intrusive thought will interact with beliefs of responsibility in ‘oversocialised’ individuals. These are the people described by Rachman and Hodgson (1980) as being ‘of tender conscience’, and therefore especially sensitive to ways in which intrusive thoughts might infringe upon their strict moral beliefs, and as being particularly likely to attempt to feel obliged to try to correct any infringements. Thus, the interaction of intrusive thoughts and strict beliefs can result in the characteristic pattern of thoughts and neutralising behaviour which develop into obsessional disorders (Salkovskis 1985). In particular, beliefs overemphasising responsibility for possible adverse consequences of one’s thoughts and actions are likely to interact with thoughts of harm and lead to the taking of precautions or corrective action (‘neutralising’) (an example was given on p. 50). Neutralising can therefore be either overt or covert behaviour, provided it is intentional and initiated as a result of the negative evaluation of an intrusive thought (see also the section below on obsessions without overt compulsive behaviour, p. 72). Figure 3.1 shows the way in which the cognitive hypothesis accounts for the development of obsessive-compulsive disorder.