What happens to electrical brain activity when anorectic adolescents gain weight?

We investigated 39 adolescent anorectic inpatients (27 cross-sectionally. 12 longitudinally) and, as controls, 12 emotionally disturbed inpatients with auditory evoked potentials (AEP) of subcortical and cortical origin. Different intensities of the stimuli were applied in an augmenting/reducing paradigm to test the ability to modulate auditory inputs. In addition, cranial CT was performed in each anorectic patient as well as in another group of 12 child psychiatric controls. Three main results were found: (1) anorectics may have difficulty in modulating auditory stimuli adequately at the subcortical level, even after gaining weight. At the cortical level, their modulation did not differ significantly from controls. (2) a systematic dissociation of the AEP amplitude response between subcortical and cortical CNS levels was seen mainly in anorectics when they had low body weight. This may suggest an uncoupling of cortical versus subcortical neuronal systems. After weight gain, anorectics had less subcortical/cortical dissociation of AEP, which was never seen in controls. Thus, to reach regular modulation of sensory information anorectics should gain normal weight and eating behavior in good time. (3) CT results showed no significant correlation with AEP findings. So far, the functional role of pseudoatrophy in anorectics remains unknown.