High (20-Hz) and low (1-Hz) frequency transcranial magnetic stimulation as adjuvant treatment in medication-resistant depression

Abstract 

Studies of repetitive transcranial magnetic stimulation (rTMS) in depression have found antidepressant effects when high frequency stimulation (HF-rTMS; >1 Hz) is applied over the left prefrontal cortex (LPF). A few studies have also reported success with low frequency stimulation (LF-rTMS) to the right prefrontal cortex (RPF). Both HF-rTMS and LF-rTMS have been reported to work better in areas with cerebral hypometabolism or hypermetabolism, respectively. Thirty medication-resistant patients with major depression were randomized into three groups. The first group received sham rTMS and the second group received active rTMS (20-Hz rTMS to the LPF and 1-Hz rTMS to the RPF). The third group, however, received active rTMS that was focused on different regions of the brain after examination with single photon emission computed tomography (20-Hz rTMS to an area of relatively low activity and 1-Hz rTMS to an area showing relatively high activation). Patients and raters were blind to the treatment condition. Comparison of the sham rTMS group with the overall group that received active rTMS revealed statistically significant changes on the Hamilton Rating Scale for Depression after 10 sessions. This study demonstrated that combined 20+1-Hz rTMS was effective, but no additional advantages were obtained by focusing rTMS on areas identified by single photon emission tomography as showing high versus low levels of functional activity.

Keywords: Prefrontal cortex, Cerebral hypometabolism, Cerebral hypermetabolism, Single photon emission computed tomography