Wiles' Study of the Effectiveness of CBT (AQA GCSE Psychology)

Antidepressant medications compared to CBT to treat depression

• For some people antidepressant medications alone are not a suitable treatment for depression (known as ‘treatment resistant’)

• Being treatment-resistant means that a patient fails to show any signs of improvement in depressive symptoms several weeks after beginning antidepressant medication

• Cognitive behavioural therapy (CBT) offers a side effects-free alternative to drug treatment 

• Combining drug therapy with CBT may increase treatment effectiveness as each treatment takes a different approach but taken together they complement each other

• Antidepressants work to reduce the symptoms of depression while CBT works to re-frame irrational thoughts and behaviours around depression

• Wiles et al. (2013) instigated CoBalT to investigate the efficacy of combined drug and CBT therapies as follows:

  • Aim: to investigate how effective combined therapy is for people with depression who are treatment-resistant

  • Sample: 469 treatment-resistant patients with depression from Bristol, Exeter and Glasgow, recruited via their GP practice

  • Procedure: the patients were randomly allocated to one of the following two conditions:

    • Condition 1: Usual care (each patient continued to take the antidepressant they had been prescribed)

    • Condition 2: Usual care + CBT (their usual antidepressant plus 12-18 sessions of CBT lasting an hour per session)

  • The patients’ symptoms were measured using Beck’s Depression Inventory (BDI)

  • Results: 

    • Condition 1: Usual care: 21.6% of the patients had a 50%+ drop in depressive symptoms

    • Condition 2: Usual care + CBT: 46.1% of the patients had a 50%+ drop in depressive symptoms, plus after one year they showed a better rate of recovery than the patients in condition 1

  • Conclusions: A combined therapy of drugs + CBT is more effective in reducing depressive symptoms than drug therapy alone

Evaluation of Wiles’ study of the effectiveness of CBT

Strengths

• Combined therapy is a more holistic approach to treating depression as it addresses and deals with the whole person (thoughts, behaviour, lifestyle) rather than simply treating the physical aspect of the disorder

• The study used the BDI to assess depressive symptoms which is a replicable measure, meaning it could be used on large samples to obtain reliable data

Weaknesses

• Use of the BDI could give rise to social desirability bias, with some participants playing down the extent of their symptoms: this would affect the validity of the findings

• The study was conducted across three cities in the UK which means that it may be ethnocentric and not generalisable to other (collectivist) cultures