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Transcranial magnetic stimulation

Auditory hallucinations or “hearing voices” is one of the most intractable and distressing symptoms of schizophrenia. Out of an estimated 3 million people who suffer from schizophrenia, 50 to 75 percent have auditory hallucinations and 25 percent of those have uncontrollable or treatment-resistant hallucinations.

The phenomenon is so disabling – one patient described up to 50 voices shouting at him – that many people with the disease resort to suicide. The search for an effective, lasting method of treatment represents a critical mental health challenge.

Now researchers are testing a method called transcranial magnetic stimulation (TMS) which has been effective during clinical trials in reducing or temporarily eliminating auditory hallucinations in schizophrenia.

How TMS is applied
Brain scanning techniques show that when patients with schizophrenia experience auditory hallucinations, there is increased activity in areas of the brain associated with hearing and speech. Preliminary studies indicate that applying a slow magnetic pulse – one per second – repeatedly to the affected area reduces “excitability” in that area. The pulses also pass the quieting effect to related areas of the brain. Results range from a decrease in symptom severity to temporary remission of hallucinations.

During TMS, a handheld electromagnetic coil is held close to the skull over the affected area and a magnetic pulse is delivered repeatedly, once or twice a day, for several days. The patient is conscious and sitting up during the application and can return to regular activities immediately after treatment. Most patients experience only a mild headache that responds to aspirin. Patients are able to continue antipsychotic medication while receiving TMS.

Studies show effectiveness
In an article in Biological Psychiatry in 2005, Dr. Emmanuel Poulet of the Federated Institute of Neurosciences (Institut Fédératif des Neurosciences) in Lyon, France, reported on a study that produced significant results in as little as five days with no adverse side effects. Dr. Poulet referred to a clinical trial at Yale-New Haven Psychiatric Hospital in which 51 percent of study subjects achieved response for at least 15 weeks after receiving TMS once a day for nine days. Poulet questioned whether applying TMS twice a day for half as many days might produce similar results in less time.

Poulet’s subjects were 10 schizophrenic patients with hallucinations who had not responded to at least two trials of antipsychotic medication. Before the trial began, patients were asked to describe the severity of their hallucinations based on seven points, including how often they occurred each day, how loud the voices were, how many were speaking and what they said. Successful results were defined as an improvement of 50 percent or more from the baseline set by the ratings.

Half the group was selected at random to receive five consecutive days of repetitive, low-frequency TMS, while the other half received “sham” sessions, which involved stimulation with a placebo coil without the electromagnetic charge. After a week’s interval, the procedure was reversed. Stimulation was given to an area on the left side of the temporoparietal cortex, a section of the midbrain associated with hearing and speech perception.

Researchers found that all seven items rated prior to the trial were significantly improved after active TMS, regardless of the order in which it was received. There was no improvement of symptoms after the sham sessions. Seven of the 10 patients showed response as early as three days into the trial, and five of them continued to show improvement after two months.

Poulet concluded that TMS was a safe and effective method for treating auditory hallucinations that did not respond to medication and recommended further study to evaluate its use as a maintenance tool.