Deep transcranial magnetic stimulation over the prefrontal cortex: Evaluation of antidepressant and cognitive effects in depressive patients

Background:

Electroconvulsive therapy (ECT) is an effective alternative for pharmacotherapy in treatment-resistant depressive patients, but the side effects limit its use. Transcranial magnetic stimulation (TMS) has been proposed as a refined alternative, but most studies do not indicate that TMS is as effective as ECT for severe depression.

Objective:

The investigators of this studypropose that the limited effectiveness of standard TMS resides in its superficial effect on the cortex, although much of the pathophysiology of depression is associated with deeper and larger brain regions implicated in the reward system. Therefore, in this study they tested the effectiveness and safety of a novel TMS coil, the ‘‘H-coil,’’ which enables direct stimulation of deeper brain regions, at the expense of focality.

Methods:

Theantidepressant and cognitive effects induced by 4 weeks of high-frequency (20 Hz) repeated deep TMS (DTMS) over the prefrontal cortex (PFC) were examined on 65 medication-free depressive patients, who have failed to benefit from prior medications. Patients were randomly assigned to various treatment configurations, differing in stimulation intensity and laterality. Effects were assessed by the 24-item Hamilton depression rating scale (HDRS-24) and several secondary outcome measures.

Results:

A significant improvement in HDRS scores was found when high, but not low, stimulation intensity was used. Several cognitive improvements were evident, and no treatment-related serious adverse events were observed.

Conclusions:

This study provides additional evidence for the feasibility and safety of the twoH-coil designs (H1/H2). The H-coils offer a safe new tool with potential for both research and clinical applications for psychiatric and neurologicaldisorders associated with dysfunctions of deep brain regions.

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