Magnetism and the brain
A related treatment, called rapid transcranial magnetic stimulation or RTMS, creates a current in the brain by using a magnetic field that crosses the exterior of the skull. It has also proved successful in treating depression. Much like the way a defibrillator works in the heart, RTMS uses a powerful magnet to deliver an electric jolt to the brain. In clinical trials, many patients who failed to respond to several other treatments improved within a week, and the vast majority were significantly better after two weeks of daily 20-minute sessions. "Transcranial magnetic stimulation is, in a way, a misnomer," says Alvaro Pascual-Leone, a neurologist at Beth Israel Deaconess Medical Center in Boston. "The main effect is not because of the exposure to the actual magnetic field but because of the way that a rapidly changing magnetic field pulse may be generating a current."
Other electromagnetic treatments are more invasive. With vagus nerve stimulation, a stimulator is slipped into the chest wall, much like a pacemaker, and electrodes are attached to the left vagus nerve in the neck. Stimulation occurs constantly; again, some with chronic, treatment-resistant depression have responded well to the procedure. Deep brain stimulation is the most invasive treatment of all. It involves an electrode implanted directly into a particular part of the brain. It was originally used to treat movement disorders like Parkinson's disease by targeting one area of the brain, but researchers found--again by serendipity--that if the electrode was slightly misplaced, it could either cause or alleviate the symptoms of depression, including hopelessness and suicidal thinking.
The notion that the brain might respond to magnets and electricity actually goes way back before the era of ECT. Franz Anton Mesmer, an 18th-century Swiss physician, developed a theory that the human nervous system was magnetized, just like the Earth. So he developed a variety of treatments using magnets and claimed to have restored sight to a blind musician and relieved the back pains of a hypochondriac. (Mesmer's most enduring contribution is actually not medical but linguistic, since his name is the source of the word "mesmerized" and he coined the expression "animal magnetism.")
What is it about the brain that makes it especially receptive to electromagnetic stimulation? A partial answer can be found in the neuron, the electrically and chemically excitable nerve cell that receives, processes, and transmits information in the brain. When neurons are activated by magnets or electricity, the nature of their signals changes--affecting everything from mood to cognition and memory.
Networks. Complex brain functions such as these are impossible to completely localize because the brain is composed of complicated, intertwined networks of cells. Much of what we do and think and feel requires the coordinated functioning of several regions in the brain; one small change in one region can cascade into dramatic changes in the whole circuit. "Electrically induced seizures actually cause turnovers of brain neurotransmitters and receptors," says Stuart Yudofsky, chairman of the department of psychiatry and behavioral sciences at Baylor College of Medicine. "We know that this is not like kicking the TV and hoping for better reception, because magnets and electricity do affect neurotransmission."
advertisement
