Rationale: There is considerable evidence showing that individuals with generalised anxiety disorder (GAD) selectively process threat-related information, e.g. they have a bias to interpret ambiguous information in a threat-related manner. Cognitive theories of anxiety, which provide the basis of cognitive-behaviour therapy, propose that such processing biases play an important role in causing and maintaining anxiety.
Objectives: Given that treatment with selective serotonin re-uptake inhibitors (SSRIs) appears to be effective for GAD, we examined whether it is successful in removing cognitive bias.
Methods: The clinical group included 19 patients with a diagnosis of GAD, and the control group consisted of a non-clinical sample of volunteers, matched for age, gender and years in education. The patients were assessed on measures of interpretative bias (homophone task), anxiety and depression before being prescribed an SSRI (paroxetine or citalopram). After 4 weeks, the cognitive task and mood measures were repeated in the patient group.
Results: Prior to treatment, the GAD group showed a significantly greater level of threat-related interpretive bias than controls. Following SSRI treatment, there were significant reductions in both interpretive bias and in anxiety levels in the GAD group. Furthermore, individuals who showed greater clinical improvement (e.g. reflected by reduced anxiety scores) showed a correspondingly greater reduction in their cognitive bias.
Conclusion: The results suggest that SSRIs are effective in modifying both subjective anxiety levels and threat-related interpretive bias.