Cognitive behavioural therapy (CBT) for depression

What CBT involves

CBT looks at how thoughts, feelings and behaviour affect each other, focusing on problems now rather than the past (NHS).

• Identify automatic negative thoughts (for example with a thought diary).
• Challenge them: what is the evidence? Is there another way to see it? (cognitive restructuring)
• Behavioural activation: plan rewarding activities to break the cycle of withdrawal.
• Homework between sessions to practise skills.

Sessions are usually weekly or fortnightly, individual or group, typically 8 to 16 sessions (NHS).

Evidence

• DeRubeis, Hollon et al. (2005): 240 patients with moderate to severe depression randomly assigned to medication (paroxetine, 120), cognitive therapy (60) or pill placebo (60). At 8 weeks, response rates were 50% (medication), 43% (cognitive therapy) and 25% (placebo); by 16 weeks both active treatments reached 58%.
• Hollon et al. (2005) followed the responders after treatment ended: 31% of those who had had cognitive therapy relapsed, compared with 76% of those withdrawn from medication and 47% of those who stayed on medication.
• Hans and Hiller (2013): a meta-analysis of 34 routine-practice studies found outpatient CBT was effective for completers, with benefits lasting at least 6 months, but roughly one in four patients dropped out.
• The NHS notes an antidepressant plus CBT usually works better than either alone.

Evaluation

• Tackles causes (negative thinking) and teaches skills, which may reduce relapse.
• No physical side effects.
• Requires motivation and effort: severe depression can make attending and doing homework hard; drop-out is common.
• Waiting times can be weeks or months (NHS), and it costs therapist time.
• May ignore circumstances: changing thoughts may not help if problems are real (debt, abuse).
• Therapist effects: in DeRubeis et al., results differed by site, suggesting therapist skill matters.

Worked example

Explain how CBT would help someone who thinks 'nobody likes me'.

1. The therapist helps the client notice the automatic thought and record when it occurs.
2. They examine the evidence: friends texted this week, a colleague invited them for lunch.
3. The thought is replaced with a more balanced one: 'some people like me.'
4. Behavioural activation: arranging to meet a friend tests the new belief and improves mood.

Answer: Identify, challenge and replace negative thoughts, then test them through behaviour.

Check yourself

1. What is the main aim of CBT for depression?
   • To uncover repressed childhood memories
   • To identify and change negative thoughts and unhelpful behaviours
   • To raise serotonin levels
   • To reduce expressed emotion in the family
   Show answer

   To identify and change negative thoughts and unhelpful behaviours. CBT targets present thoughts and behaviour.

2. The NHS says a CBT course usually lasts 8 to 16 sessions. If sessions are fortnightly, how many weeks would 16 sessions take?
   Show answer

   32 weeks. 16 x 2 = 32 weeks.

3. DeRubeis et al. (2005) studied 240 patients; the medication group was twice the size of each of the other two groups. How many patients were in the medication group?
   Show answer

   120 patients. Groups in ratio 1 : 2 : 1, so 4 parts = 240, 1 part = 60; medication = 2 x 60 = 120.

4. What did DeRubeis and Hollon's research find about relapse?
   • Medication prevented relapse better than cognitive therapy
   • Placebo was most effective
   • Cognitive therapy was better than medication at preventing relapse after treatment ended
   • Nobody relapsed in any group
   Show answer

   Cognitive therapy was better than medication at preventing relapse after treatment ended. Cognitive therapy had a lasting advantage.

5. What is behavioural activation?
   • Planning rewarding activities to break the cycle of withdrawal and low mood
   • Taking an SSRI each morning
   • Being hypnotised
   • Avoiding social situations
   Show answer

   Planning rewarding activities to break the cycle of withdrawal and low mood. Activity improves mood and tests beliefs.

6. Explain one weakness of CBT as a treatment for depression.
   Show answer

   CBT requires motivation and effort such as homework, but severe depression reduces motivation, so some people drop out or do not benefit.. Low motivation in depression makes the demands of CBT hard.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification (issue January 2026)
• Pearson IAL Psychology component guide: WPS04 (Issue 2, November 2024)
• NHS: Depression in adults, treatment
• DeRubeis et al. (2005), Cognitive therapy vs medications in the treatment of moderate to severe depression, Archives of General Psychiatry 62
• Vanderbilt University news (2005) on Hollon et al. (2005), Prevention of relapse following cognitive therapy vs medications, Archives of General Psychiatry 62
• Pearson IAL Psychology summary of studies: WPS04

Last updated 8 November 2026. Spotted a mistake? Tell us.