Electrophysiological effects of deep brain stimulation in anorexia nervosa

Objective: To study deep brain stimulation (DBS)-induced electrophysiological changes over time in patients with anorexia nervosa (AN). Methods: We performed EEG recordings on 4 AN patients treated with DBS at 3 time points, and on 8 age-matched controls. We extracted oscillatory power in the alpha and beta bands, connectivity and global network organization parameters based on graph theory. Results: We found strong significant within-subject changes in alpha and beta power over time. Nominally significant effects were observed for posterior left (L) alpha (p = 0.034) and anterior/posterior L scalp areas (p = 0.034 and p = 0.013, respectively), however, multiple testing indicated that the effects are heterogeneous across subjects. We found V-shaped curves over time for average functional connectivity. This was largely re-established at the final time-point. The graph-theoretical measures showed similar V-shaped effects consistent with an initially disordered network state. Conclusion: Within-subject effects of stimulation were large, widespread over frequencies, and visible across wide brain areas and networks. Prolonged stimulation seemed to reinstate organization in the functional brain networks. Our results support the observations that effects of DBS are not merely local, but influence widespread pathological network activity and that, after an initial period of disorganisation, the brain adapts to the stimulation. Significance: A better understanding of the electrophysiological effects of DBS may allow us to personalize and optimize the intervention and thereby further improve effectiveness in AN.