Psychopathology and Other Mental Health Challenges in Siblings of Patients with Child- or Adolescent-Onset Anorexia Nervosa: A Systematic Review with a Sex/Gender Perspective

Background/Objectives: Anorexia nervosa (AN) is a severe psychiatric-metabolic disorder with high morbidity and mortality, profoundly impacting family systems. Siblings of patients with AN constitute a vulnerable group, yet there is a lack of specific, quantitative evidence on their mental health status, particularly when examined from a sex/gender perspective. This review aimed to synthesize existing evidence on the prevalence of psychiatric symptoms, diagnoses, and other mental health challenges in siblings of individuals with AN and critically analyze it from a sex/gender perspective. Methods: Following PRISMAguidelines, a systematic search was conducted across five databases (April–May 2025). The protocol was registered in PROSPERO (CRD420251025535). Sixteen studies published between 1983 and 2022 met eligibility criteria. Results: Included studies were rated as high or moderate quality, and overall risk of bias was estimated as low–moderate. Only half of the studies included brothers, and overall quality assessment from a sex/gender perspective was modest. Dimensional psychopathology assessments found increased prevalence of both internalizing and externalizing symptoms in siblings compared to controls, although siblings were generally more like controls than affected probands in psychometric evaluations. The few studies based on clinically diagnosed psychopathology state that siblings are at increased risk of several mental health disorders. Conclusions: Specific quantitative evidence on psychiatric diagnoses, psychopathology and other mental health challenges in siblings of individuals with AN is relatively scarce and biased, particularly by systematic exclusion of externalizing symptoms and male siblings. Future translational research should be designed and interpreted using a sex/gender perspective and prioritize systematic assessment by clinicians.