Comorbidity of anorexia nervosa and schizophrenia: A systematic review

Research on the intersection between eating disorders and schizophrenia (SCZ) has mainly focused on binge eating, since increased appetite and metabolic side effects are common during antipsychotic use. However, the prevalence of restrictive eating and anorexia nervosa may be higher in people with SCZ than in the general population, and evidence suggests shared genetic liability for SCZ and anorexia nervosa (AN). The aim of this systematic review was to examine the prevalence, psychological and biological mechanisms, and theoretical underpinnings underlying the co-occurrence of AN and SCZ. We identified 40 articles that met inclusion criteria. Evidence suggested that the prevalence of AN in patients with SCZ is higher than would be expected in the general population; conversely, evidence regarding the prevalence of SCZ in AN was mixed. Psychological mechanisms underlying AN in people with SCZ fell into three categories: positive symptoms, negative symptoms, and atypical pathways. A limited literature generally supports the hypothesis of higher prevalence of AN in patients with SCZ, but there are few studies in this area. Studies of the prevalence of SCZ in AN yield more mixed findings, although these studies are also relatively small and few. Further, studies of both types tend to include only clinically ascertained samples, which limits the generalizability of findings beyond patients. Larger, better-designed studies may improve identification and treatment of people with co-occurring SCZ and AN.