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October 11, 2004
TMS and schizophrenia
Transcranial Magnetic Stimulation in the investigation and treatment of schizophrenia: a review
H. Magnus Haraldsson, Fabio Ferrarelli, Ned H. Kalin and Giulio Tononi.
Transcranial magnetic stimulation is a technology that is increasingly being harnessed for use in psychiatry both therapeutically and as a tool for research. It works based on creating a targeted magnetic field that can interact with brain cells and cause them to be excited and fire more frequently. There are 2 main types of TMS and both have different uses. The most common side effect of TMS is headache.
There are 2 kinds of TMS. One offers a single pulse, while another technique utilizes more rapid, repeating pulses. In each, a coil is placed on the patients head and the magnetic field is applied. There are different shaped coils (circular or figure of eight) intended to reach either a more diffuse or more focused area of the brain. The circular coils tend to give a more diffuse area of stimulation. A number of variables influence how accurately a specific brain area can be stimulated with TMS. These variables include the intensity of stimulation, the shape and orientation of the stimulating coil and the excitability, type and orientation of the neurons in the area of stimulation. One can use one or two coils to acheive different electrical effects in the brain and to target different areas.
Is TMS effective in treating mental illness? Well, the research is just beginning...There is some evidence that it might help with depression when applied to either the Left or Right prefrontal cortex of the brain. Research has been limited until recently be difficulty in creating a "sham" condition. It is important to have a "sham" that seems like the patient is getting TMS, and appears/feels exactly the same, but does not have magnetic current that has any effect. This is needed to help eliminate placebo effect and more certainly attribute any benefits seen to the TMS than to the patient's psychological hope that the treatment is better. There is now a new sham technique so hopefully research into TMS will increase. It is still not known exactly what settings or locations to place the coils are best in schizophrenia.
Results with TMS have at best been mixed so far. Most studies have not shown a significant benefit, but not much is known about the most optimal way to utilize the technology. There is some hope that perhaps if the part of the brain that processes auditory hallucinations receives a signal from TMS it might decrease the hallucinations. This however, will be a long way off from being clinically useful.
Overall, TMS is a new technology that may eventually have clinical benefit and currently is helpful in researching isolated parts of the brain. It may prove more beneficial as an adjunct to other technologies or may ultimately be useful on its own in treating schizophrenia.
This work was supported by a grant from the families of Donald and Patricia Cheney and Jack and Patricia LanePosted by Jacob at October 11, 2004 11:35 PM | TrackBack