High (15 Hz) and low (1 Hz) frequency transcranial magnetic stimulation have different acute effects on regional cerebral blood flow in depressed patients.

BACKGROUND: High and low frequency repetititve transcranial magnetic stimulation (rTMS) are both effective in treating depression but have contrary effects on motor cortical activity. This study aimed to understand further the mechanisms of action of high and low frequency rTMS by examining their acute effects on regional cerebral blood flow (rCBF) in depressed patients. METHOD: Eighteen depressed subjects underwent brain single photon emission computerized tomography (SPECT) scanning using split-dose 99mTc-HMPAO, and were examined during sham and active rTMS to the left prefrontal cortex, at 15 Hz or 1 Hz (N=9 each). Relative rCBF changes were examined by statistical parametric mapping and by regions of interest analysis. RESULTS: High (15 Hz) frequency rTMS resulted in relative rCBF increases in the inferior frontal cortices, right dorsomedial frontal cortex, posterior cingulate and parahippocampus. Decreases occurred in the right orbital cortex and subcallosal gyrus, and left uncus. Low (1 Hz) frequency rTMS led to increased relative rCBF in the right anterior cingulate, bilateral parietal cortices and insula and left cerebellum. High frequency rTMS led to an overall increase, whereas low frequency rTMS produced a slight decrease, in the mean relative rCBF in the left dorsolateral prefrontal cortex. CONCLUSIONS: High (15 Hz) and low (1 Hz) frequency rTMS led to different frontal and remote relative rCBF changes, which suggests different neurophysiological and possibly neuropsychiatric consequences of a change in frequency of rTMS.

Double-blind controlled investigation of bilateral prefrontal transcranial magnetic stimulation for the treatment of resistant major depression.

BACKGROUND: The efficacy and safety of bilateral prefrontal repetitive transcranial magnetic stimulation (rTMS) for treating resistant major depression were examined in a double-blind, placebo-controlled study. METHOD: Nineteen medication-resistant depressed subjects were randomly assigned to 3 weeks of active or sham rTMS. Effects on mood and neuropsychological function were assessed. RESULTS: Both groups improved significantly in mood over the 3 weeks, but there was no significant difference between active and sham treatments. There were no significant neuropsychological effects. CONCLUSIONS: Bilateral rTMS was not superior to sham in treating resistant depression in this pilot study, but caused no neuropsychological impairment.

Right versus left prefrontal transcranial magnetic stimulation for obsessive-compulsive disorder: a preliminary investigation.

BACKGROUND: There is preliminary evidence that repetitive transcranial magnetic stimulation (rTMS) may be useful for the treatment of obsessive-compulsive disorder (OCD), but no definitive study has been published, and the effect of laterality of stimulation is uncertain. METHOD: Subjects (N = 12) with resistant OCD were allocated randomly to either right or left prefrontal rTMS daily for 2 weeks and were assessed by an independent rater at 1 and 2 weeks and 1 month later. RESULTS: Subjects had an overall significant improvement in the obsessions (p < .01), compulsions (p < .01), and total (p < .01) scores on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) after 2 weeks and at 1-month follow-up. This improvement was significant for obsessions (p < .05) and tended to significance for total Y-BOCS scores (p = .06) after correction for changes in depression scores on the Montgomery-Asberg Depression Rating Scale. There was no significant difference between right- and left-sided rTMS on any of the parameters examined. Two subjects (33%) in each group showed a clinically significant improvement that persisted at I month but with relapse later in I subject. CONCLUSION: A proportion (about one quarter) of patients with resistant OCD appear to respond to rTMS to either prefrontal lobe, although in the absence of a sham treatment group in this study, we cannot rule out the possibility of this being a placebo response. This treatment warrants further investigation to better establish its efficacy and examine the best parameters for response.