Efficacy of cognitive behaviour therapy in generalized anxiety disorders. Results of a controlled clinical trial (Berlin CBT-GAD Study).
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.
Linden
M
M
Research Group Psychosomatic Rehabilitation, University Hospital Benjamin Franklin, Berlin, Germany. linden@zedat.fu-berlin.de
Zubraegel
D
D
Baer
T
T
Franke
U
U
Schlattmann
P
P
D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000523:psychology / Q000628:therapy*; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D012720:Severity of Illness Index