A systematic review comparing atypical anorexia nervosa and anorexia nervosa

A description of atypical anorexia nervosa (atypical AN) was provided in DSM-5 in 2013 and a sizable literature has since developed describing the clinical features of individuals with atypical AN and comparing them to those of individuals with anorexia nervosa (AN) and those of healthy individuals. The purpose of this study was to conduct a systematic review of this literature.

A systematic review following PRISMA guidelines was conducted of studies published since 2013 that compared the clinical characteristics of individuals with atypical AN to those of individuals with AN and/or healthy controls. Meta-analyses were conducted when similar measures were reported in three or more studies.

Twenty-four publications met criteria for inclusion. Their results indicated that the level of eating disorder-specific psychopathology is significantly higher among individuals with atypical AN than among controls and as high or higher as among individuals with AN while levels of non-eating disorder psychopathology are similar. Individuals with atypical AN experience many of the physiological complications associated with AN, but some complications appear less frequent.

The psychological symptoms and physiological complications of individuals with atypical AN are generally similar to those of individuals with AN, although there may be differences in the frequency of some physical complications. Little information is available on the course, outcome, and treatment response of individuals with atypical AN. In addition, full diagnostic criteria for atypical AN have not been developed, and the nosological relationship of atypical AN to established eating disorders such as bulimia nervosa is unclear.

Atypical anorexia nervosa as described in the DSM-5 identifies individuals with many of the psychological characteristics of typical anorexia nervosa who, despite significant weight loss, are not underweight. The current systematic review found that the psychological symptoms and physiological characteristics of individuals with atypical AN are generally similar to those of individuals with AN, although there may be differences in the frequency of some physical complications.