Rapid mood-elevating effects of low field magnetic stimulation in depression

Background We previously reported rapid mood elevation following an experimental magnetic resonance imaging procedure in depressed patients with bipolar disorder (BPD). This prompted the design, construction, and testing of a portable electromagnetic device that reproduces only the rapidly oscillating (1 kHz, <1 V/m) electromagnetic field of the experimental procedure, called low field magnetic stimulation (LFMS). Methods We used a randomized, double blind, sham controlled treatment protocol to study the effects of LFMS in a large group of stably medicated, depressed patients with either BPD (n = 41) or major depressive disorder (n = 22). Subjects received a single, 20-minute treatment. Change in mood was assessed immediately afterward using a visual analog scale (VAS), the 17-item Hamilton Depression Rating Scale (HDRS-17), and the Positive and Negative Affect Schedule scales. Results Substantial improvement (>10% of baseline) in mood was observed following LFMS treatment relative to sham treatment for both diagnostic subgroups for our primary outcomes, the VAS and the HDRS-17. These differences were not statistically significant in primary analyses stratifying by diagnosis but were significant in secondary analyses combining data across the two diagnostic groups (p =.01 VAS, p =.02 HDRS-17). Rapid improvement in mood was also observed using the Positive and Negative Affect Schedule scales as secondary measures (positive affect scale p =.02 BPD, p =.002 combined group). A finite element method calculation indicates a broad penetration of the LFMS electric field throughout the cerebral cortex. Conclusions Low field magnetic stimulation may produce rapid changes in mood using a previously unexplored range of electromagnetic fields.