Cognitive therapy is a highly effective treatment for mood disorders. Discuss.
As Karasu noted in 1982, there has historically been a polarization of the field of treatment of all psychological conditions; on the one hand, there is a camp which touts psychotherapy as the most effective and superior form of treatment, and on the other, there are those who champion the cause of pharmacotherapy as the most effective treatment.[1] In Karasu’s words, this separation between the two disciplines is likely to be “symptomatic of the post-Cartesian mind-body dichotomy at the core of modern medicine.” Statements about the effectiveness of the one or the other, which is often held to be thus the superior of the two, should be viewed through this lens.
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Before we can address the question of whether or not cognitive therapy is a highly effective treatment for mood disorders, we need to be clear about what we mean by “cognitive therapy” and “mood disorders”. Mood disorders are typically taken to cover a range of depressive disorders which include both unipolar depression and bipolar disorder, and which might range from full-blown major depression through to the display of some depressive symptoms.
According to Blackburn et al., citing Beck’s (1967, 1976) cognitive theory of depression, someone who is depressed will view themselves as a “loser” and will interpret all their experiences in terms of their own inadequacies. They will anticipate that their present difficulties will continue indefinitely and, blaming themselves, they will become increasingly self-critical. As well as this negative view of the self, the world and the future, they will also make “logical systematic errors”, which will lead them to draw erroneous conclusions about their experiences. Such errors might include personalization, over-generalization, magnification and minimization. They will also have “dysfunctional basic premises” or “idiosyncratic schemas”, which help them to sieve, categorize and act upon information that they receive from their experiences of the world around them..[2]
The aim of cognitive therapy is to change these negative schemas through the use of a variety of cognitive and behavioural techniques. The approach is problem-oriented and time-limited, typically lasting about 12 weeks.[1] The most frequently reported forms of cognitive therapy in the literature are cognitive behavioural therapy (CBT) and interpersonal therapy (IPT). Other techniques include psychoeducation, psychodynamic focal therapies and mindfulness-based cognitive therapy (MBCT). Throughout this paper, the terms cognitive therapy and psychotherapy are used interchangeably.
Among these different cognitive therapy techniques, CBT is the one most often considered in the literature, and it is widely reported to be effective, but how do we decide if something is highly effective or not? To decide how effective a treatment is, we need to consider the available evidence. What follows is not a full and systematic review of the literature, which is beyond the scope of this paper, but rather, a look at some of the available evidence to date on the subject and an outline of the key issues. In it, I propose that the evidence for the effectiveness of cognitive therapy as a treatment for depression is not unequivocal and that a more integrated approach would be more beneficial.
Writing in 1981, Blackburn et al. cite a study by Rush et al. (1977), which was one of the earlier studies comparing cognitive therapy and pharmacotherapy, and which showed that cognitive therapy was superior to the drug imipramine in outpatients with unipolar depression in both level of response and rate of premature treatment termination.[2] They attempted to replicate that study, but comparing a range of drugs with cognitive therapy, rather than just imipramine, and they also tested a combination of both cognitive therapy and pharmacotherapy. They found cognitive therapy to be only minimally more effective than the drugs in a group of mildly to moderately depressed hospital outpatients, but significantly more so than drugs alone in general practice, both alone and in combination with drugs. In both groups, using a combination of cognitive therapy and pharmacotherapy produced the greatest effect of all.[1] However, as the researchers do note, they used no objective method to assess patients’ compliance with the pharmacotherapy regimen.[2]
In their study of cognitive behaviour therapy (CBT) and assertion training (AT) groups for patients with depression and comorbid personality disorders, Ball et al. found CBT alone to produce a significant improvement in all the outcomes measured, including at follow-up.[3] However, the group that received a combination of CBT and AT showed only minimal improvement on the social competence and anxiety measures[4], and only two of the four measures that were significant immediately after the treatment were still significant at follow-up.[5] In short, the presence of a comorbid personality disorder appeared to impede the response to CBT and AT and the outcomes at follow-up.[6] Since depressed patients have high rates of comorbid personality disorders[7], these results have significant implications for the use of cognitive therapy in combination with other forms of non-pharmacotherapy for the treatment of depression.
The use of a much briefer CBT protocol in this study (15 hours over five weeks), which as Ball et al. note is about half that in most studies in the CBT outcomes literature, should be noted. If briefer protocols like this can produce appreciable long-term improvements in the prognosis of depression, then this is likely to be more cost-effective than the longer protocols typically employed.[8] However, since the study was uncontrolled, there may well be other explanations for the results. Clearly more studies, particularly randomised controlled trials (RCTs), of cognitive therapy in this under-researched group are needed.
In their recent review of psychotherapy and pharmacotherapy treatments for mood and anxiety disorders, Otto et al. noted that in terms of acute outcomes, both CBT and pharmacological treatments have repeatedly been shown to be efficacious and in most cases to offer an approximately equal effect, though there are some suggestions that CBT is more tolerable and especially more cost-effective.[1] CBT has, however, consistently shown a strong relapse-prevention effect, in direct contrast to pharmacotherapy, which often requires ongoing treatment to prevent relapse.[2]
It has been suggested that pharmacotherapy and cognitive therapy have differential effects, the former on symptom formation and affective distress, and the latter on interpersonal relations and social adjustment, each activated and sustained on a different time schedule, the pharmacological treatments sooner and over a shorter duration and the psychotherapeutic treatments later and over a longer duration.[3] There is some evidence that CBT and pharmacotherapy may produce similar limbic and cortical changes in the brain, but also that they target different primary sites.[4] There is, moreover, some evidence of complementary modes of action among patients who fail on one form of treatment but gain benefit from the other.[5] Such complementarity favours a more integrated approach to the treatment of depression that combines the beneficial effects of both pharmacotherapy and cognitive therapy, but is there any evidence that such an approach does indeed work?
In their 1986 review of the evidence for the effectiveness of combined psychotherapy and pharmacotherapy for the treatment of depression, Conte et al. found a combination of the two approaches to be more effective than either of the treatments alone, though the apparently additive effect was not a strong one. Conte et al. highlight a number of possible explanations for the observed effect, including the high drop-out rates in the studies they considered, making generalization difficult, the differential response to pharmacotherapy or psychotherapy dependent on whether the diagnosis was endogenous or situational, questions about whether it is either ethical or even practically possible to have a placebo in psychotherapy trials, and the low power of their own overall approach to their review.[1] Conte et al. also suggest that whilst their results might support the additive model, they might also be explained if some patients benefit more from one treatment and some more from the other.[2] The non-standard nature of diagnoses, therapies, training and experience of therapists also makes comparisons and generalizations difficult, if not impossible.[3],[4]
In 1997, Thase et al. suggested that their mega-analysis comparing psychotherapy with psychotherapy-pharmacotherapy combinations provided evidence of the superiority of a combination of psychotherapy and pharmacotherapy over psychotherapy alone for the more severely-depressed outpatients, both in terms of overall recovery rates and a shorter time to recovery.[5] However, none of the patients older than 60 received psychotherapy and none with non-recurrent depression were in the combination group.[6] The less seriously depressed patients treated with interpersonal therapy (IPT) or CBT alone achieved results comparable to those in the combination group.[7] As it is, this evidence for the effectiveness of a combined approach is ambiguous.
There are further problems with this study, though. Comorbid patients were excluded[8] – and as has been noted earlier, comorbidity is typically associated with poorer outcomes – and a disproportionately large number of the patients had recurrent depression, so if the combination of psychotherapy and pharmacotherapy is more effective in this sub-group, this will lend a skew to the picture suggesting effectiveness in all severely-depressed patients.[9]
Finally, inasmuch as this is a mega-analysis, the non-standard nature of diagnoses, therapies, training and experience of therapists highlighted earlier makes generalizations very difficult, a problem noted by the authors of this study also.[1]
In their 2004 review, Pampallona et al. concluded that a combination of pharmacotherapy and psychotherapy produced a greater improvement in depression scores than pharmacotherapy alone.[2] Pampallona et al. note that the addition of psychotherapy does appear to reduce the degree of non-response and increase adherence, but they question whether this is because psychotherapy has a genuine therapeutic effect or whether it is merely enhancing compliance with the pharmacological regimen, and suggest further studies with an improved range of outcome measures, including patient satisfaction, well-being and social functioning.[3]
In their 2005 review, however, Otto et al. found that acute outcome studies with depressed outpatients provided only limited support for the theory that a combination of pharmacotherapy and psychotherapy is more efficacious than either approach alone. They did find higher rates of treatment response, but the differences were small and not statistically significant.[4] Adding psychotherapy to the acute phase of a pharmacological treatment regimen was found to offer a comparable efficacy to a long-term pharmacological regimen in helping to prevent more than one relapse.[5] Otto et al. did find that adding CBT to a pharmacological course of treatment improved medication adherence, reduced the impact of psychosocial stressors such as negative life events and anxiety comorbidity, prevented or limited the severity of prodromal episodes, and directly improved outcomes in bipolar disorder.[6]
The evidence, then, for the effectiveness of cognitive therapy as a treatment for depression is not unequivocal. It does appear to improve outcomes, but it is unclear whether to a greater or approximately equivalent extent to pharmacological approaches to treatment. Whilst the evidence for adopting a combined approach is also not clear-cut, since the vast majority of people with depression experience multiple episodes over their lifetime, and are especially prone to relapses shortly after their first episode[1], and in light of both the possibly complementary mode of action of cognitive therapy and pharmacotherapy and the possibly harmful effects of long-term anti-depressant use, a more effective long-term strategy might involve the integration of both approaches. This might involve a drugs-based regimen in the earlier stages of depression, to treat symptoms and affective distress, and cognitive therapy throughout, to treat the interpersonal and social dimensions of depression, enhance compliance to the drugs-based regimen and treat and prevent relapses.
Vos et al. modeled the impact of adopting a longer-term maintenance strategy on the burden of major depression, and suggested that this could avert half the depression occurring in the five years after an episode.[2] A combined strategy would appear therefore to show some promise in reducing the quite significant disease burden placed by depression on society and improving the lives of those who suffer from it. Further robust controlled trials are clearly needed to assess the effectiveness of cognitive therapy, both alone and in combination with pharmacotherapy, as a part of an integrated long-term strategy.
References
Ball, J., Kearney, B., Wilhelm, K., Dewhurst-Savellis, J. & Barton, B. (2000) ‘Cognitive behaviour therapy and assertion training groups for patients with depression and comorbid personality disorders’, Behavioural and Cognitive Psychotherapy 28, 1, 71-85
Blackburn, I. M., Bishop, S., Glen, A. I. M., Whalley, L. J. & Christie, J. E. (1981) ‘The Efficacy of Cognitive Therapy in Depression: A Treatment Trial Using Cognitive Therapy and Pharmacotherapy, each Alone and in Combination’, Brit J Psychiatry 139, 181-189
Conte, H., Plutchik, R., Wild, K. V. & Karasu, T. (1986) ‘Combined Psychotherapy and Pharmacotherapy for Depression: A Systematic Analysis of the Evidence’, Arch Gen Psychiatry 43, 471-479
Karasu, T. (1982) ‘Psychotherapy and Pharmacotherapy: Toward an Integrative Model’, Am J Psychiatry 139, 9, 1102-1113
Klein, D. F. (2000) ‘Flawed Meta-Analyses Comparing Psychotherapy with Pharmacotherapy’, Am J Psychiatr 157, 1204-1211
Otto, M. W., Smits, J. A. J. & Reese, H. E. (2005) ‘Combined psychotherapy and pharmacotherapy for mood and anxiety disorders in adults: Review and analysis’, Clinical Psychology: Science and Practice 12, 1, 72-86
Pampallona, S., Bollini, P., Tibaldi, G., Kupelnick, B. & Munizza, C. (2004) ‘Combined Pharmacotherapy and Psychological Treatment for Depression: A Systematic Review’, Arch Gen Psychiatry 61, 7, 714-719
Thase, M. E., Greenhouse, J. B., Frank, E., Reynolds, C. F., Pilkonis, P., Hurley, K., Grochocinski, V. & Kupfer, D. J. (1997) ‘Treatment of Major Depression With Psychotherapy or Psychotherapy-Pharmacotherapy Combinations’, Arch Gen Psychiatry 54, 1009-1015
Vos, T., Haby, M., Barendregt, J. J., Kruijshaar, M., Corry, J. & Andrews, G. (2004) ‘The Burden of Major Depression Avoidable by Longer-term Treatment Strategies’, Arch Gen Psychiatry 61, 11, 1097-1103
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