Efficacy of Cognitive Behaviour Therapy in Generalized Anxiety Disorders
Results of a Controlled Clinical Trial (Berlin CBT-GAD Study)Linden M. · Zubraegel D. · Baer T. · Franke U. · Schlattmann P.
aResearch Group Psychosomatic Rehabilitation, and bDepartment of Psychiatry and Psychotherapy, Biostatistical Division, Charité, University Hospital Benjamin Franklin, Berlin and cDepartment of Behavioural Medicine, BfA-Rehabilitation Centre Seehof, Teltow/Berlin, Germany
Background: Generalized anxiety disorders (GAD) are amongst the most prevalent mental disorders. Recent studies have suggested that cognitive behaviour therapy (CBT) is an effective treatment for GAD. A controlled clinical trial was done to evaluate the efficacy of CBT treatment in outpatients with pure GAD who were treated by a therapist working in routine care. Methods: Seventy-two outpatients, fulfilling GAD criteria according to DSM-IV, were included in the study. From this group, 36 patients (CBT-A) were randomly assigned to 25 sessions of CBT and the other 36 formed a contact control group (CCG). After the contact control period (CC period), these patients were also treated with CBT (CBT-B), allowing not only a parallel group comparison but also an A-B comparison. Therapists were licensed full-time psychologists who worked routinely in outpatient care and had a professional training in CBT. Treatment was done in accordance with a manual, and treatment conformity was controlled by several methods. Results: The reduction in the score on the Hamilton Anxiety Observer Rating Scale was 6.4% (1.5 points) in the CCG, 35.4% (9.5 points) in the CBT-A and 47.3% (10.3 points) in the CBT-B. In the self-rating Spielberger State-Trait Anxiety Inventory, a reduction of 2.7% was seen in CCG, 14.6% in CBT-A, and 11.6% in CBT-B. According to the Clinical Global Impression Rating, 65.6% of patients were still at least moderately ill at the end of the CC period, while this rate was 33.4% at the end of CBT-A, or 15.7% at the end of CBT-B. All these differences between treatment and control group are statistically highly significant. The clinical improvement remained stable over a follow-up period of 8 months. Conclusions: CBT is an effective method of treatment for GAD. Differences between control and treatment group are comparable to or larger than those reported in studies on antidepressant drugs.