High Frequency Deep TMS over the Bilateral Insula is Associated with Increased Degree Centrality in the Prefrontal Cortex of Obese Subjects: Preliminary Evidence

Journal: Brain Stimulation 12(2):499 (2019)

Authors: F Devoto, A Ferrulli, L Zapparoli, S Massarini, C Verga, G Banfi, E Paulesu, L Luzi

Background:

Obese subjects can be considered “food addicted”. Since there is growing evidence for the role of deep Transcranial Magnetic Stimulation (Deep TMS™) in reducing craving for different addictions, the authors proposed high frequency (HF) Deep TMS as a mean to reduce food craving and body weight.

Objective:

Exploring plastic changes associated with HF Deep TMS in obese patients, by measuring the regional brain network centrality (degree centrality, DC) in the patients’ resting-state fMRI brain patterns.

Methods:

The authors used a data-driven approach and computed the regional DC for each patient before the beginning of the treatment (DCT0) and by the end of the treatment (DCT1). For each voxel in the brain, the DC was calculated as the average of the significant functional connections that each voxel has with the remaining voxels in the brain. Then, the difference between DCT1and DCT0(△DC=DCT1-DCT0) was computed. Finally, an independent samples T-test was used to test the differences in △DC between HF (n=6) and Sham (n=6) groups. All patients underwent 15 sessions (3 per week for 5 weeks).

Results:

The HF group, compared with the Sham, showed a greater increase of DC by the end of the 5 week-treatment in a cluster centered in the left superior medial frontal gyrus and encompassing the anterior portion of the supplementary motor area (p<0.005, cluster-level FEW corrected). No significant DC increase was found in sham.

Conclusions:

These preliminary findings suggest the presence of neurofunctional plastic changes associated with excitatory Deep TMS over both insulae. Specifically, these results suggest a mechanism through which excitatory Deep TMS can empower self-control and inhibitory processes to resist the feelings of craving. If confirmed in a larger sample of obese patients the present results constitute the evidence of the mechanism of action of high frequency TMS as novel treatment of obesity.