A new type of brain stimulation device for combating difficult-to-treat cases of major depressive disorder is likely to break into the large American market soon. Its maker, Jerusalem-based Brainsway, plans to apply to the U.S. Food and Drug Administration for permission to market the device this month. The move follows initial results from a large-scale trial of the system, in which 30.4 percent of treated patients went into remission and 36.7 percent showed significant improvement. Research into device-based treatments for psychiatric problems has grown rapidly, and if the FDA gives its go-ahead, Brainsway’s system will become the fourth device-based therapy to go on the market since 2005.
Deep transcranial magnetic stimulation (TMS), as its name suggests, uses magnetic fields to stimulate activity in structures deep in the brain. The patient wears a helmet in which powerful, specially designed electromagnets have been carefully positioned. When a pulse of electricity flows through the magnets’ coils, the resulting magnetic field induces current to flow through a portion of the brain.
There are subtle differences between deep TMS and repetitive transcranial magnetic stimulation (rTMS), a brain stimulation tool widely used in research and also marketed as a treatment for depression. The electromagnetic elements in deep TMS are designed to produce a magnetic field that reaches its greatest strength deep within the brain. Ordinarily, magnetic fields fall away quickly inside the brain, but the orientation and structure of the coils in deep TMS lessens that effect. “The concept was to reduce the rate of reduction of the magnetic field as a function of distance,” says Abraham Zangen, coinventor of the technology. In contrast, rTMS typically uses a single coil that produces a tightly focused field just a few centimeters below the brain’s surface.