Clinical heterogeneity of feeding and eating disorders: using personality psychopathology to differentiate “simplex” and “complex” phenotypes

Background: To investigate Feeding and Eating Disorders (FED) heterogeneity based on the co-occurrence of FED symptoms and personality psychopathology, on the hypothesis that empirical profiles would not confirm current FED categories but identify unique phenotypes carrying different levels of clinical complexity. Methods: Latent Profile Analysis profiled FED patients based on the assessment of both FED symptoms, through the Eating Disorders Inventory, third version (EDI-3), and personality characteristics, through the Minnesota Multiphasic Personality Inventory-2. Then, profiles were compared across socio-demographic and clinical characteristics. Results: Among 109 eligible patients, three FED profiles were identified: (i) FED simplex (low eating symptoms, absence of dysfunctional personality); (ii) FED simplex-severe (high eating symptoms only); and (iii) FED complex-severe (high eating symptoms and dysfunctional personality). Despite an uneven distribution (χ2(6) = 15.20, adjusted-p = 0.029), FED profiles did not unequivocally confirm clinical diagnoses (e.g., Anorexia Nervosa). A difference in Body Mass Index (BMI) was observed (K(2) = 15.06, adjusted-p = 0.001), but lower BMI did not identify the most severe group. Profiles differed in EDI-3 overall scores (e.g., Eating Disorder Risk Composite: K(2) = 43.08, adjusted-p < 0.001), Body Uneasiness Test Global Severity Index (GSI: K(2) = 29.33, adjusted-p < 0.001), Binge Eating Scale severity (K(2) = 25.49, adjusted-p < 0.001), number of psychiatric (K(2) = 8.79, adjusted-p = 0.021) and personality diagnoses (K(2) = 11.86, adjusted-p = 0.005), and Symptom Checklist-90-Revised GSI (F(2,103) = 37.68, adjusted-p < 0.001), with FED complex-severe patients being generally the most severely impaired in terms of FED symptoms, body concerns, depersonalization, and psychiatric comorbidities. Conclusions: Findings support the hypothesis of distinguishing FED simplex and complex phenotypes, based on the co-occurrence of dysfunctional personality, with implications for FED severity and clinical practice.