Cognitive behavioural therapy for depression, rather than referring to a single system of therapy, now more accurately describes a range of practices derived from the original work by Aaron Beck (Beck et al. 1979), focusing on the thinking patterns and associated emotional, behavioural and physiological systems operating within the depressed individual. Problematic schema, acquired in and reflecting the course of development are retained into later life and can be triggered by thematically congruent events. Such triggering events are argued to lead to characteristic negative automatic thoughts, thinking errors and erroneous or negatively biased (Power & Dalgleish, 1997) information processing and associated behavioural, emotional and physiological responses. The first goal of CBT is the identification of any such systematic errors and the second is the modification of thinking and reasoning patterns to replace them with evidence-based and rationale alternatives, thus facilitating behavioural, emotional and physiological change through the same interconnected systems.
Cognitive behavioural therapy for depression is the most commonly used and researched of the psychological therapies in the NHS. It is also commonly thought to be the psychological therapy with the most clearly established evidence base (NICE, 2004). It has been repeatedly shown to offer equivalent benefit to established anti-depressant medication for the treatment of depression (Hollon et al., 1992; Murphy et al., 1984; Rush et al., 1977) and superior outcome to no treatment or wait-list control. However its relative efficacy in relation to other psychological therapies is not yet as clearly established, perhaps confusing quantity for quality. Dobson's (1989) meta-analysis found CBT to be more effective than no treatment, behavioural treatment alone and anti-depressants but Robinson et al. (1990) revised this to report equivalent efficacy to anti-depressant medication when controlling for therapist allegiance. Gloaguen et al. (1998) in a meta analysis of almost 3 000 patients, concluded that CBT was superior to no treatment and all other treatment methods, with the exception of behaviour therapy, although this is challenged by Parker, Roy & Eyers (2003) who cite evidence that contradicts the conclusions drawn. De Rubeis & Crits-Christoph (1998) cite three large-scale studies in which CBT was shown to be equivalent but not superior to other forms of psychotherapy - namely IPT (Elkin et al, 1989), psychodynamic interpersonal psychotherapy (Shapiro et al., 1994) and behaviour therapy (Jacobson & Hollon, 1996), findings that are at odds with the predominance of CBT in clinical practice. In smaller studies a similar pattern has been found. Ward et al. (2000) found CBT to be superior to TAU in general practice but showed no significant difference to non-directive counselling at the end of treatment and no significant difference to TAU after one year. Gloaguen et al.'s (1998) meta-analysis of patients with mild to moderate depressions concluded that cognitive therapy (CT) patients had 29 % greater improvement than placebo/waiting list subjects, 15% greater improvement than patients receiving anti-depressant medication and 10% more improvement than patients receiving other therapies, with the exception of behaviour therapy where no difference in outcome was found. It was also of note that there was between trial heterogeneity in the comparison with other therapies creating difficulty in generalising the overall finding to each of the individual therapies included.
Such findings do not argue against CBT as a treatment for depression. On the contrary they demonstrate its consistently robust performance in the face of many comparative evaluations. However they highlight the relative absence of studies with depressed patients in which CBT was found to be superior to an alternative psychological treatment, a superiority tacit in the predominance of this model of practice. Cognitive behavioural therapy has demonstrated equivalence in good quality pharmacology studies (De Rubeis et al., 1999; Hollon et al., 1992; McKnight, Nelson-Gray & Barnhill, 1992). Hollon et al. (1992) also found no difference in CBT outcome with more severely depressed patients, in contrast to the findings of the TDCRP (Elkin et al. 1995). De Rubeis et al. (1999) also conducted a meta-analysis of four studies comparing CBT and medication for patients with severe depression. Direct comparisons between the two lines of intervention showed no significant differences but overall effect sizes favoured CBT. Deckersbach, Gershuny & Otto (2000) argue that although there is scant evidence beyond trend level for the additive effect of CBT and anti-depressant medication with mild to moderate depression, more evidence exists with the chronically and more severely depressed, perhaps offering combined independent effects rather than a synergistic mode of action. Keller et al. (2000) conducted a multi-site trial (n = 681) in which the CBT focused primarily on interpersonal issues, including interactions with the therapist. A significantly higher proportion of patients receiving combined treatment rather than those receiving CBT or medication alone met responder and remission criteria.
In addition to the benefits of CBT as an acute intervention, follow-up data from a number of studies suggest that CBT offers longer term relapse prevention effects (Evans et al., 1992; Kovacs et al., 1981; McLean & Hakstian, 1990; Simons et al., 1986), resulting in two to three times as many CBT patients remaining well as medication patients. Parker, Roy & Eyers (2003), however, note that naturalistic follow-up confuses the prophylactic effects of acute CT and the impact of maintenance treatment in sustaining initial gains. Fava et al. (1996) concluded that CBT for residual symptoms reduces the risk of relapse in depressed patients compared to clinical management and, although the overall effect faded after four years, CBT patients experienced fewer relapses than the control group (Fava, 1998a, b). Paykel et al. (1999) also found that CBT for residual depressive symptoms resulted in 38 % lower rates of relapse and symptoms persistence than clinical management alone over 68 weeks follow up. Blackburn & Moore (1997) found no difference between groups who received either CBT or medication for 2 years following a 16-week acute intervention. Interestingly Gortner et al. (1998) found no difference in relapse prevention rates for full CBT and its component parts in a two-years follow up to the dismantling study previously cited.
Cognitive behavioural therapy offers a present focused, collaborative and problem oriented approach to the treatment of depression, targeting characteristic patterns of thinking, behaviour and emotional regulation. Specific emphasis is given to returning the individual to productive and pleasurable activities and the more successful management of any skills deficits and thinking patterns that create a barrier to this. Such deficits may be longstanding or more directly reflective of the current depressed state. This intervention of collaboratively set programmes of activity scheduling encourages individuals to do what they planned rather than what they feel in the midst of a depression episode. The specific skills training provided, for example social or problem-solving skills, will reflect the presenting difficulties for the individual and their contribution to the depressed state. In parallel with this and informed by it is consistent attention to maladaptive thinking and reasoning style, with a view to developing and reinforcing a more adaptive and evidence-based cognitive style. This integrated approach acknowledges the interconnections between emotions, cognition, behaviour and physical state and capitalises on this by approaching the system from a number of different angles in order to intervene where change is possible. This integrated approach is contained within the case formulation, which guides the choice of intervention and provides a framework from which to understand the presenting difficulties.
The assessment phase of CBT, as with any psychotherapy, aims to foster a safe and collaborative relationship. Details are gathered about the nature and extent of the current depressive difficulties and these are placed in context with a history of depression to date as well as recent precipitating events and losses consequent to the depression, both of which are more common in depressed populations. Systematic assessment is completed with standardised forms, such as the CBT-compatible Beck Depression Inventory (BDI) (Beck et al., 1961) and clinical interviews. Given the prominence of formative experiences in the CBT formulation, care is taken to listen for the character of and meaning given to these early experiences. Cognitive behavioural therapy provides the individual with a strong component of psychoeducation, immediately promoting an evidence-based approach to presenting problems. The cognitive model of depression with negative cycles of interacting thoughts, depressed affect, decreased activity and withdrawal is offered as framework within which to understand current experience. Written material outlining the cognitive model and basic information about depression is provided early in the therapy relationship to be reviewed as a between-session task. This provides a means of both understanding current activation of the depressive cycle and the developmental origins of depressive thinking and behavioural patterns. The level of intervention varies across different CBT models, with some restricting attention to the surface level negative automatic thoughts and associated responses, whereas others (Young, Weinberger & Beck, 2001) direct attention to the systems of belief or schema that underlie the current manifestations. The provision of this framework of understanding is a powerful intervention for some individuals, helping them to step outside of the automatic patterns and take up a more objective perspective.
Psychoeducation also provides guidance on the individual's role within the therapy. CBT is a collaborative exercise and as such promotes active participation on the part of the patient. The patient has the role of co-therapist rather than passive recipient of treatment and as such is required to make active use of the information provided. Preparing the patient for this role is an important early task of CBT.
The collaborative nature of CBT is illustrated at the start of each of the treatment sessions, when a shared agenda is negotiated to serve as the basis for the session to follow. This should reflect a review of the important or salient points from the previous meeting, difficulties that may have emerged and a detailed examination of progress with the negotiated homework tasks to be completed between each of the sessions. The specific nature of the homework task will reflect the stage of therapy and the nature of the presenting difficulty and consequently may shift across and between behavioural and cognitive themes. The issues addressed will consistently be examined in the light of the case formulation and with reference to the agreed treatment goals.
Monitoring the completion of these negotiated tasks forms the largest part of the treatment sessions of CBT. The detailed examination of the homework tasks provides the material to be used for cognitive restructuring exercises or behavioural experiments. The systematic nature of this examination provides an opportunity to model an adaptive problem solving approach and the individual is encouraged to arrive at his or her own conclusions by means of Socratic questioning and guided discovery, which support the investigation but does not impose conclusions or judgements.
Examination of the individual's thought processes in relevant situations - those associated with depressed mood - is facilitated by systematic recording of thoughts in daily record sheets, which prompt consideration of supportive and contradictory evidence, vulnerability to characteristic reasoning errors, alternative explanations and connection to emotional response. The patient is supported in examining these incidents in more detail during the session, approaching them as testable hypotheses rather than automatically accepted facts. At the most basic level Socratic questioning helps the individual to re-examine the recorded examples in order to derive an evidence based conclusion. However the supportive relationship between the co-therapists can also be a valuable resource through the use of shared meaning and metaphor and role plays which bring the scenario to life emotionally for the individual and facilitate the exploration of different perspectives, potentially highlighting the limitations of the initial formulation. Such work will assist the exploration of the underlying beliefs about self and others, which provide the backdrop for recurrent automatic thought and feeling responses. Drawing individual examples together to identify recurrent themes can help broaden the impact of interventions.
Examining previous experience also provides the basis for behavioural experiments and activity scheduling in anticipation of the next session. In this way the guided discovery continues outside of the sessions as the patient explores the possibilities raised by the previous discussion and works to address identified areas of overactivity or underactivity. The therapist also has an important role to support the patient in maintaining attention on the depression specific incidents and avoided or diminished pleasurable activity. In this way activity remains goal directed and weekly recordings become a valuable resource charting the impact of the previous activities and the connection to depressed mood and thinking.
Just as CBT sessions start with a collaboratively agreed agenda so they end with a mutually acceptable summary. This provides an opportunity to review important material, monitor the patients retention and understanding, highlights misconceptions and as the sessions continue provides an opportunity for the transfer of responsibility from the therapist to the patient. This process is mirrored in the approach to ending therapy as a whole, which should be maintained in focus from an early stage. Cognitive behavioural therapy offers a particular strength in directing attention to relapse prevention in the latter sessions, anticipating potential areas of difficulty and rehearsing constructive responses. Given the recurrent nature of depression this is another opportunity to model the application of evidence based information in practice.
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