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Cognitive Behaviour Therapy May Help Adult Anxiety Disorders: Presented at ADAA

By Mike Fillon

SAVANNAH, Ga -- March 11, 2008 -- Cognitive behaviour therapy (CBT) -- a psychotherapeutic approach aimed at modifying negative cognitions, assumptions, beliefs, and behaviours -- may be effective for treating certain adult anxiety disorders, according to results of a study presented here at the Anxiety Disorders Association of America (ADAA) 28th Annual Conference.

The meta-analysis found CBT to be particularly effective as a treatment for obsessive-compulsive disorder (OCD) and acute stress disorder (ASD). The advantage of CBT over placebo did not depend on placebo modality, number of sessions, or study year.

While there have been numerous studies examining the efficacy of CBT for adult anxiety disorders, there has been a lack of a systematic review of randomised, placebo-controlled trials, noted lead researcher Jasper A.J. Smits, PhD, Assistant Professor of Psychology, and Director, Anxiety Research and Treatment Program, Southern Methodist University, Dallas, Texas.

"In particular, a number of frequently cited meta-analyses of CBT for anxiety disorders have included studies that vary greatly with respect to control procedures, which range from wait list, alternative treatments, and placebo interventions that were evaluated with or without randomisation," Dr. Smits said in his presentation on March 7. "Other studies fail to include any control groups."

In this new study, Dr. Smits and colleagues conducted a search of treatment outcome studies that randomly assigned adult patients meeting anxiety criteria as set out in the Diagnostic and Statistical Manual of Mental Disorders, Third or Fourth Editions, to either CBT or placebo up until March 1, 2007. They also examined reference lists from identified articles and asked international experts for their input for identifying eligible studies.

Of the initial 1,165 studies identified, the researchers found 27 studies that met all inclusion criteria. Independently, the researchers identified the eligible studies and selected for each study the continuous measures of anxiety severity. Dichotomous measures reflecting treatment response and continuous measures of depression severity were also collected.

Data were extracted separately for completer and intent-to-treat analyses. They both showed that there were no significant differences in attrition rates between CBT and placebo. Random effect models of completer samples yielded a pooled effect size of 0.73 (95% confidence interval [CI], 0.88-1.65) for continuous anxiety severity measures and 0.45 (90% CI, 0.25-0.65) for depressive symptom severity measures. The pooled odds ratio for completer treatment response rates was 4.06 (95% CI, 2.78-5.92).

The researchers concluded that as reflected by medium to large effect sizes for measures of anxiety disorder severity, CBT yields greater benefits than placebo treatments. "We found the effects were significantly greater for ASD relative to all other disorders with the exception of OCD," said Dr. Smits. "Moreover, CBT for OCD was more effective than CBT for [panic disorder]."

He also said they found that a comparison between CBT and placebo by diagnostic groups showed that CBT significantly outperformed placebo in reducing depression only in PTSD and OCD.

"We believe these findings support the specificity of CBT for most of the anxiety disorders," he concluded.

[Presentation title: Cognitive-Behavioral Therapy for Adult Anxiety Disorders: A Meta-Analysis of Randomized Placebo-Controlled Trials. Abstract 5]

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