Psychosocial and pharmacological interventions for cluster a personality disorders: A systematic review and two exploratory meta-analyses

Despite an overall prevalence of about 4% and a possible association with well-studied conditions such as schizotypy, little is known about effective treatments for Cluster A personality disorders (PDs), that is, paranoid, schizoid, and schizotypal PD. The aim of this systematic review and meta-analysis was to conduct a narrative synthesis of existing randomized controlled trials and explore the effectiveness of psychosocial and pharmacological treatments for these disorders. Nineteen studies including 468 participants diagnosed with any one of the three Cluster A PDs were included in the systematic review. Data from 291 (k = 5) and 213 (k = 5) participants were included in two different meta-analyses evaluating the reduction of distinctive clinical features and the increase of general functioning following treatment, respectively. All the treatments in meta-analyses reported a low overall attrition rate (0.23). The two meta-analyses showed medium-to-large effect sizes (g = .60-.91), but were limited by small sample sizes and large heterogeneity. Collected findings suggest that treatments for paranoid, schizoid, and schizotypal PD may be feasible and effective. We discuss implications for further research.