Health psychology (option): CBT for anxiety disorders and its effectiveness

CBT for anxiety

Anxiety disorders (such as generalised anxiety disorder, GAD) involve excessive, hard-to-control worry and physical tension. CBT assumes anxiety is maintained by negative automatic thoughts and unhelpful behaviours (avoidance, reassurance-seeking) that stop the person learning their fears are exaggerated.

Typical components (usually weekly sessions with a therapist, individually or in a group):

1. Psychoeducation: understanding anxiety and the fight-or-flight response.

2. Identifying and challenging thoughts: catastrophising ('if I fail I'll lose everything'), overestimating danger; examining evidence; recording thoughts in a diary.

3. Behavioural work: gradual exposure to feared situations, reducing avoidance, behavioural experiments to test predictions.

4. Relaxation and problem-solving skills, homework and relapse prevention.

In the UK the NHS usually offers talking therapies such as CBT before medication for GAD.

Effectiveness

• Hofmann and Smits (2008): a meta-analysis of 27 randomised placebo-controlled trials found CBT efficacious for adult anxiety disorders, with people about four times as likely to respond to CBT as to placebo (pooled odds ratio 4.06). Effects were largest for OCD and acute stress disorder and smallest for panic disorder; the authors noted considerable room for improvement.
• Avdagic et al. (2014): group CBT and group ACT for GAD both produced significant reductions in worry, anxiety, stress and depression, maintained at 3-month follow-up.

Testing a CBT outcome: Wilcoxon

Invented data for practice: worry scores for 10 clients before and after CBT.

Before: 32, 28, 35, 30, 26, 38, 29, 33, 31, 27

After: 24, 25, 29, 31, 20, 27, 29, 22, 26, 23

• Differences (before - after), dropping the zero: 8, 3, 6, -1, 6, 11, 11, 5, 4 (N = 9).
• Ranks of the absolute differences: 7.0, 2.0, 5.5, 1.0, 5.5, 8.5, 8.5, 4.0, 3.0.
• Sum of positive ranks = 44.0; sum of negative ranks = 1.0; T = 1.0.
• Critical value (N = 9, one-tailed, p ≤ .05) = 8; T must be equal to or less than it. 1.0 ≤ 8, and scores fell as predicted, so worry was significantly lower after CBT.

Wilcoxon critical values (Pearson table); T must be equal to or less than the critical value

Evaluation

• Strengths: strong evidence from randomised controlled trials and meta-analyses; tackles the thoughts and behaviours that maintain anxiety, so gains tend to last after treatment ends (Avdagic et al.: maintained at follow-up); no physical side effects; group formats are cost-effective.
• Weaknesses: needs motivation and effort (homework, facing fears), so some drop out (23% of the CBT group in Avdagic et al.); takes weeks and needs trained therapists, so waiting lists can be long; may not suit people who find it hard to reflect on their thoughts; focuses on the individual rather than life circumstances causing stress.

Worked example

In Avdagic et al. (2014), 6 of the 26 people allocated to CBT dropped out. What percentage is that, and why does it matter?

1. 6 / 26 x 100 = 23.1%.
2. High drop-out means the people who finished may be the most motivated, which could make CBT look more effective than it is for everyone.

Answer: 23.1% dropped out.

Check yourself

1. Thinking 'if I make one mistake at work I'll be sacked and lose my home' is an example of
   • exposure
   • catastrophising
   • relaxation
   • problem-focused coping
   Show answer

   catastrophising. Jumping to the worst outcome.

2. Why does CBT for anxiety include gradual exposure to feared situations?
   • To increase serotonin
   • To make the client more anxious permanently
   • To replace medication completely
   • To reduce avoidance and show that feared outcomes do not happen
   Show answer

   To reduce avoidance and show that feared outcomes do not happen. Avoidance maintains anxiety.

3. How many randomised placebo-controlled trials were in Hofmann and Smits's (2008) meta-analysis?
   Show answer

   27. 27 trials.

4. For the invented worry data, the positive ranks total 44.0 and the negative ranks total 1.0. What is T?
   Show answer

   1. T is the smaller total: 1.0.

5. With T = 1.0, N = 9 and a one-tailed critical value of 8 at p ≤ .05, what do you conclude?
   • Significant, because T is equal to or less than the critical value
   • Not significant, because T is less than the critical value
   • Significant only if T is greater than the critical value
   • The Wilcoxon test cannot be used for before and after scores
   Show answer

   Significant, because T is equal to or less than the critical value. For Wilcoxon, T must be equal to or less than the critical value.

6. Which is a weakness of CBT for anxiety?
   • It has serious physical side effects
   • It has never been tested in trials
   • It needs motivation and effort, so some people drop out
   • It only works with medication
   Show answer

   It needs motivation and effort, so some people drop out. Homework and exposure are demanding.

7. Explain one advantage of CBT over SSRIs for treating anxiety.
   Show answer

   CBT tackles the thoughts and behaviours that maintain anxiety, so improvements tend to last after treatment ends, whereas symptoms often return when SSRIs are stopped; CBT also has no physical side effects.. CBT benefit compared with drugs.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification, Issue 6 (November 2024, first assessment January 2026)
• Hofmann and Smits (2008), Cognitive-behavioral therapy for adult anxiety disorders: a meta-analysis of randomized placebo-controlled trials, Journal of Clinical Psychiatry 69(4)
• NHS: Generalised anxiety disorder, treatment
• Pearson IAL Psychology summary of studies: WPS03
• Pearson International A Level Psychology sample assessment materials (Wilcoxon critical values table)

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