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ViewAttendees 5

Symposia

Eating Disorders

Unraveling complexity: Novel mechanistic insights into "atypical" anorexia nervosa

5 - (SYM 49) Neurobiological Mechanisms of Atypical Anorexia Nervosa

Saturday, November 16, 2024
8:30 AM – 10:00 AM EST
Location: Congress C, 4th Floor, Loews
Abstract Body
DSM-5 atypical anorexia nervosa (Atyp-AN) resembles its full-threshold namesake in that it is characterized by restrictive eating, fat phobia, and overvaluation of weight and shape, but it is distinguished by a weight that remains within or above normal limits, whereas weight in anorexia nervosa (AN) is significantly low. Our team’s longitudinal data demonstrate prospective bidirectional crossover between Atyp-AN and AN, suggesting that for some, an atypical presentation may represent a prodromal or partially recovered state in those with lifetime AN. To clarify boundaries between Atyp-AN and AN, our Multidisciplinary Eating Disorders Research Collaborative has investigated the neurobiological bases of these conditions and their relation to illness course using research domain criteria (RDoC) informed designs. Herein, we leverage data collected from a RDoC-aligned study of adolescent and young adult females with AN, Atyp-AN, and healthy controls who completed diagnostic interviews and self-report measurements, magnetic resonance imaging for evaluation of brain structure and paradigm-related neural activation, and blood draws for assessment of proteomics and appetite-regulating hormones. In general, we identified several neurobiological similarities between AN and Atyp-AN compared to healthy individuals: Reduced gray matter volume in parietal, temporal, and frontal cortices in both AN and Atyp-AN compared to healthy controls; greater neural activation in food motivation regions when passively viewing food vs. objects in comparison to that activation in healthy controls; differences from healthy controls in circulating inflammation protein expression levels, including proteins which are pathologically related to systemic-inflammatory autoimmune disorders; and altered levels of appetite-regulating hormones. Few specific differences emerged between AN and our cohort of Atyp-AN, who included individuals below 90% of expected body weight, but above the low-weight AN threshold. While larger and more diverse samples are needed, these early data suggest that a strict definition of the low-weight criterion in AN may not be clinically meaningful given the lack of both neurobiological and clinical differences observed between AN and Atyp-AN.