Risk factors that predict future onset of restricting versus binge/purge anorexia nervosa in women: an exploratory study

Recent prospective studies identified risk factors that predict future onset of anorexia nervosa (AN), but none have differentiated between those predicting restrictive (AN-R) versus binge-eating/purging (AN-BP) AN subtypes. Identifying shared versus unique risk factors may clarify whether these subtypes reflect distinct subtypes of AN or phases of the same disorder. This exploratory study combined data from four eating disorder prevention trials involving young women at risk for eating disorders (N = 1,952, mean age = 19.7 years) and collected annual diagnostic data over a 3-year follow-up. We assessed which baseline variables predicted future onset of AN-R and AN-BP, including subthreshold cases classified as Other Specified Feeding and Eating Disorder. Over 3-year follow-up, 34 participants developed AN-R and 24 developed AN-BP. Elevated negative affect and low BMI emerged as shared risk factors for both AN subtypes. Unique risk factors for AN-R were elevated thin-ideal internalization, fear of weight gain, and dietary restraint. Psychosocial impairment was the only unique predictor for AN-BP. The presence of distinct risk factors suggests that AN-R and AN-BP represent distinct subtypes rather than developmental stages of the same disorder. Shared risk factors should be prioritized as targets in prevention efforts for AN, particularly negative affect, and low prodromal BMI.