The Efficacy of the Growing Pro-social Program in Reducing Anger, Shame, and Paranoia over Time in Male Prison Inmates: A Randomized Controlled Trial

Objectives: This randomized controlled trial aimed to assess the efficacy of a cognitive-behavioral group program, Growing Pro-Social (GPS), in reducing anger, shame, and paranoia over time in Portuguese male prison inmates. Methods: Participants were randomized to the GPS treatment (n = 121) or control group (n = 133). The State-Trait Anger Expression Inventory, the Other as Shamer Scale, and the Paranoia Scale were completed at baseline, at the middle of treatment, at posttreatment, and at 12 months' follow-up. Intervention effects were tested with latent growth curve models (LGCM). Results: At baseline, no significant differences between groups were found. Results from LGCM showed that condition was a significant predictor of change observed in all outcome measures over time. While treatment participants showed a significant increase in anger-control over time, controls presented a significant decrease over time in this same variable. For the remaining dimensions of anger, as well as for external shame and paranoia, while the treatment group showed a significant decrease over time, the control group showed a significant increase or no change. Conclusions: These results pointed out the GPS's ability to promote significant change in cognitive and emotional relevant variables associated with antisocial behavior.