EFFECT OF BDNF MET66VAL POLYMORPHISM ON HIPPOCAMPAL STRUCTURE AND FUNCTION: A META-ANALYSIS

Abstract

The results from a meta-analysis of 70 Rational-Emotive Therapy (RET) outcome studies are reported. A total of 236 comparisons of RET to baseline, control groups, Cognitive Behavior Modification, Behavior Therapy, or other psychotherapies are examined. The results indicate that subjects receiving RET demonstrated significant improvement over baseline measures and control groups. Effect-size was significantly related to therapist experience and to duration of the therapy, but there were no significant differences in effect-size between those studies that used psychotherapy clients compared to those using students as subjects. Those comparisons that were rated high in internal validity (random assignment, low attrition, and outcome measures low in reactivity), had significantly higher effect-sizes than medium validity studies. Outcome measures rated as low in reactivity (i.e., those measures which did not have an immediately discernable relationship with the treatments being assessed) had significantly higher effect-sizes than more reactive measures. Contrary to other reviews using the narrative review method, RET was found to be an effective form of therapy. This conclusion, however, was tempered by methodological flaws in the studies reviewed, such as lack of follow-up data and information regarding attrition rates.