Brain Structure and Function in Adolescents with Atypical Anorexia Nervosa

Abstract: Atypical anorexia nervosa (AAN) has a high incidence in adolescents, resulting in significant morbidity and mortality. The weight loss is generally less pronounced than that experienced in full-syndrome anorexia nervosa (AN), but the medical consequences can be as severe. Neuroimaging could improve our knowledge regarding the pathogenesis of eating disorders, however research on adolescents is limited, and no neuroimaging studies have been conducted in AAN. In paper I, we investigated brain structure through a voxel-based morphometry analysis in 22 drug-naïve adolescent females newly-diagnosed with AAN, and 38 age- and sex-matched healthy controls. In Paper II, we investigated white matter microstructural integrity on 25 drug-naïve adolescent patients with AAN and 25 healthy controls, using diffusion tensor imaging with a tract-based spatial statistics approach. No differences in brain structure could be detected, indicating preserved regional grey matter volumes and white matter diffusivity in patients with AAN compared to controls. These findings suggest that previous observations of brain structure alterations in full syndrome AN may constitute state-related consequences of severe underweight. Alternatively, the preservation of brain structure might indeed differentiate AAN from AN. In paper III, we investigated resting-state functional connectivity in 22 drug-naïve adolescent patients with AAN, and 24 healthy controls. We report reduced connectivity in patients in brain areas involved in face-processing and social cognition, while an increased connectivity, correlating with depressive symptoms, was found in areas involved in the multimodal integration of sensory stimuli, aesthetic judgment, and social rejection anxiety. These findings point toward a core role for an altered development of socio-emotional skills in the pathogenesis of AAN. In Paper IV, we investigated neural connectivity underlying visual processing of foods with different caloric content in a sample of 28 adolescent females diagnosed with AAN, and 33 age- and sex-matched healthy controls. Our results showed higher connectivity in patients in pathways related to the integration of sensory input and memory retrieval, in response to food with high caloric content. This, however, was coupled to lower connectivity in salience and attentional networks, and lower connectivity between areas involved in visual food cues processing and appetite regulatory regions. Thus, despite food with high caloric content is associated to greater processing of somatosensory information in patients, it is attributed less salience and engages patients’ attention less than food with low caloric content.