2 - (SYM 132) Understanding Atypical Anorexia Nervosa: Demographic Characteristics and Clinical Severity of a Treatment Seeking Sample

Background: Atypical anorexia nervosa (AAN) represents a large and growing portion of eating disorder diagnoses. Individuals with AAN experience profound medical, psychological, and physiological complications at severity levels similar to, or even above, those of individuals with AN. However, AAN is less frequently seen in treatment settings, perpetuating misunderstanding of this life-threatening disorder and delaying vital treatment.

Methods: Participants were female patients at a residential treatment center who presented with either AAN (n=231) or AN (n=1579). Patients completed surveys at intake and discharge. Descriptive statistics were used to examine clinical and demographic characteristics of patients with AAN. Independent samples t-tests were used to compare patients with AAN to AN on measures of clinical severity.

Results: The AAN sample was predominantly white (83.9%) and on average 23.5 years old (SD=9.0). Mean age of onset was 14.3 years old (SD=5.4) with an average duration of illness of 9.3 years (SD=8.6). Individuals with AAN reported on past month behaviors including: binge eating (M=1.5, SD=4.5), vomiting (M=10.6, SD=22.2), excessive exercise (M=7.5, SD=10.2), and laxative use (M=3.5, SD=8.4). Compared to AN, patients with AAN reported significantly more episodes of vomiting (p=.03), and more comorbid diagnoses (p< .001). 39.4% of the AAN sample met criteria for PTSD, compared to 28.2% of the AN sample. When reporting on experiences of trauma, 56.1% of patients with AAN endorsed experiencing emotional abuse.


Conclusions: This study adds to the limited body of research characterizing AAN. Average age of onset aligns with research regarding age of onset of AN, suggesting a similar timeline of illness. Patients with AAN were more likely to engage in vomiting, which has been associated with higher medical acuity and greater overall psychopathology. Patients with AAN had more comorbid diagnoses, underscoring the heightened overall clinical severity of this population. A majority of patients with AAN reported experiencing emotional abuse, which may be linked to experiences of weight stigma and discrimination. Future research should examine the timeline of illness onset to treatment initiation in this population, as overestimated importance of weight categories may prevent individuals from receiving care in a timely manner, thus exacerbating symptoms. Finally, research should examine weight bias and discrimination in experiences of trauma, as this may impact clinical severity in patients with AAN.