Understanding implicit and explicit learning in adolescents with and without anorexia nervosa

BACKGROUND: Cognitive disturbances such as impairments in learning are thought to play a role in adult Anorexia Nervosa (AN). It is remains unclear to what extent these disturbances result from starvation of the brain, or relate to an abnormal premorbid cognitive profile. This study investigates learning processes in adolescents with AN, hypothesizing that implicit learning is intact, as found previously in explicit learning tasks. Secondly, we hypothesized that anxiety and depression symptoms, inherent to AN, are associated to learning processes in AN. METHODS: In total 46 adolescents diagnosed with AN and 44 control participants were administered an implicit category learning task in which they were asked to categorize simple perceptual stimuli (Gabor patches) based on a linear integration (i.e., an implicit task) of orientation and spatial frequency of the stimulus. A subgroup of adolescents (n = 38) also completed a task assessing explicit learning. RESULTS: Model-based analyses indicated that adolescents with AN performed significantly more accurately compared to their healthy peers regardless of whether they used the optimal strategy or not. Depression and anxiety did not relate to learning performance in the AN group. CONCLUSIONS: Overall, our findings of augmented implicit and explicit learning in adolescents with AN corroborate recent studies that suggested higher stimulus-response learning during prediction error paradigms. Learning disturbances in adult AN may then be at least partly due to long-term malnourishment, highlighting the importance of early recognition and refeeding in treatments for AN.