Anorexia nervosa (AN) and bulimia nervosa (BN) are serious, complex psychiatric illnesses classified in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). While they are recognized as distinct diagnoses, their clinical manifestations often overlap, pointing to deep commonalities between the two conditions. The primary difference between them lies in the individual’s body weight status, but the underlying psychological distress and dangerous behaviors position them on a shared spectrum of disorders. Understanding these common threads highlights the shared vulnerabilities inherent to both disorders.
Shared Underlying Psychological Factors
Both AN and BN are driven by an intense and irrational fear of gaining weight or becoming fat, which persists even in the face of medical evidence. The disorders share a profound disturbance in the way an individual experiences their body shape and weight, known as body image disturbance. A person’s self-worth becomes unduly influenced by their perception of their body shape and weight, making these external factors the primary measure of personal value.
This cognitive distortion creates a constant internal pressure to achieve or maintain a specific physique, often leading to feelings of inadequacy or low self-esteem. The pursuit of a thin ideal is frequently tied to a desperate search for a sense of control over one’s life or emotions. In both conditions, the manipulation of food intake or weight is used as a maladaptive mechanism to cope with overwhelming internal distress, such as anxiety or anger.
Overlapping Compensatory Behaviors
Compensatory behaviors are actions taken to counteract the effects of eating, and their presence is a significant commonality between BN and the Binge-Eating/Purging Type of AN. Self-induced vomiting is a highly recognized method of purging used in both disorders, often serving to alleviate the guilt associated with consuming calories. The misuse of medications also provides a shared avenue for compensation, including the abuse of laxatives, diuretics, or enemas.
Non-purging compensatory behaviors are also common to both conditions, most notably excessive exercise. This exercise is typically driven and compulsive, performed despite fatigue, injury, or medical contraindications. The diagnostic crossover between AN and BN further illustrates the fluidity of these behaviors, with approximately one-third of individuals with AN crossing over to BN at some point during their illness.
High Rates of Comorbid Conditions
AN and BN exhibit high rates of comorbidity with other mental health disorders, suggesting shared underlying psychological and biological vulnerabilities. At least 80% of individuals with either disorder have at least one additional psychiatric diagnosis over their lifetime. Mood disorders, particularly major depressive disorder, are prevalent, occurring in 50% to 75% of patients. Anxiety disorders and Obsessive-Compulsive Disorder (OCD) symptoms also affect a substantial number of individuals. Additionally, both disorders show increased rates of substance use disorders and a shared link to a history of trauma.
Systemic Physical Health Risks
Both disorders pose severe risks to nearly every system in the body, primarily due to the physiological stress of malnutrition, starvation, or purging behaviors. A major shared danger is the development of severe, life-threatening electrolyte imbalances. Purging behaviors can lead to hypokalemia, a dangerously low level of potassium that disrupts heart rhythm and function. The cardiovascular system is severely affected, with cardiac issues being a leading cause of death in severe cases.
Individuals may experience bradycardia or cardiac arrhythmias, which can lead to sudden cardiac arrest. Hormonal disruptions are also common, including amenorrhea and low sex hormones, which lead to reduced bone mineral density, resulting in osteopenia or osteoporosis. Shared gastrointestinal problems include reflux esophagitis and ulcers resulting from repeated exposure to stomach acid.