The impact of personality disorders and personality traits on psychotherapy treatment outcome of eating disorders: A systematic review

A significant proportion of those with eating disorders (EDs) do not respond to first-line treatments. This systematic review was conducted to identify whether personality disorders (PDs)/traits predict or moderate ED treatment outcomes and whether these outcomes were differentially influenced by ED or PD diagnostic subtypes, or treatment approach. A comprehensive systematic literature search was conducted using the PRISMA guidelines. A total of seven randomised controlled trials (RCTs) plus four follow-up studies were reviewed investigating the impact of PD and PD traits on treatment outcomes for EDs. The majority indicated that PD had some impact on treatment outcomes. Outcome measures and time-point measurements varied across studies. Included studies suggested that bulimia nervosa treatment outcomes were not hindered by co-morbidity of borderline PD; however, psychiatric impairment remained high at post-treatment and follow-up. Cluster C PDs were found to negatively impact treatment outcomes for binge ED and attrition rates for anorexia nervosa. Included studies suggested that interventions that addressed aspects of personality pathology showed greater main effects for ED treatment outcomes. There is an urgent need for future RCTs on ED treatments to include routine measures of core personality features to allow their impacts to be more thoroughly examined and for psychotherapies to be tailored accordingly.