The present paper aimed (1) to review the literature to examine the effectiveness of CBT as treatment for PDA and (2) to evaluate whether the efficacy of CBT treatments is related to the change to cognitive processes that are postulated to be important in the cognitive models of PDA. A literature review of CBT studies in the area of PDA was conducted using both descriptive and quantitative (meta-analysis) procedures. In all, 35 studies published between 1969 and 1996 were included. The results show that CBT is an effective treatment for PDA. However, the contribution of cognitive processes to this disorder and the role that they play in the successful outcome of CBT remain unclear and in need of further empirical investigation. At present, CBT treatment provides limited support to validate the cognitive models of PDA.