In January 2007, the US FDA concluded that rTMS was safe, but they were unconvinced of its effectiveness. Their conclusion was arguable, but the arguments fell short. For one thing, the initial application compared rTMS to ECT. It was safer, but less effective. Also, another study compared rTMS to sham treatments. The stats showed it was statistically effective, but the p-value was 0.057. It had to be 0.050, or less, to be convincing.
TMS, by the way, is a way of manipulating brain function. It can be used for research. It also can be used clinically, especially if done repetitively in the same area (rTMS). It is being investigated for use in treatment of depression, migraine, fibromyalgia, autism, and other conditions.
One limitation is that the devices generally used can't stimulate brain that it deeper than about 1-2 centimeters into the cortex. Now, there is a company called Brainsway that has developed a device that can penetrate 5-6 cm in a clinically useful fashion.
Of course, it has been possible to generate deep magnetic fields for a
long time. Just use more power. The problem is that
the brute-force approach increases the risk of tissue damage, or of
nasty adverse events, such as seizures. The Brainsway device
uses multiple small coils. These produce fields that overlap.
It is possible to position them so that the greatest overlap
occurs in the area where the stimulation is desired.
This is explained in a recent article in the MIT magazine, Technology Review.
They had good reults in a preliminary study with 50 persons with treatment-refractory depression. Perhaps more interesting, is the potential to broaden the clinical applications:
A quick fix for addiction? Probably not. But if they could reduce or eliminate drug craving, that would be a useful adjunct to traditional abstinence-based treatments.
On the other hand, if it is possible to treat addiction, it might also be possible to cause addiction. That is a bit of a disturbing notion. (In fact, it was anticipated by the science-fiction author Larry Niven.)
But we already have plenty of things that cause addiction, so I don't think this would change the world, really.
As for the treatment of mood disorders, the folks at Brainsway think that their device will be better than regular rTMS, because it can penetrate deep enough to reach the limbic system. This has led them to posit a hypothesis:
This hypothesis strikes me as dreadfully simplistic, so I am skeptical of its value. With the human brain, as complex as it is, most initial hypotheses are false. But you have to start somewhere.
The FDA still has to figure out how they are going to evaluate the treatment. It is a novel treatment, so companies that try to get approval from the FDA have to do some guesswork to try to anticipate what will be needed. That is unfortunate, but true.
Despite the bureaucratic hurdles, the Brainsway approach sounds promising. Perhaps they will be able to get that magic p-value of 0.050.
This is explained in a recent article in the MIT magazine, Technology Review.
A Gentler Way to Jump-Start the Brain
By Jennifer Chu
May 19, 2008
...In order to reach deeper regions, researchers would have to increase the intensity of the electric current flowing through the coil, which could induce painful side effects such as seizures and tissue damage.
Instead, Abraham Zangen, one of two inventors of Brainsway's deep TMS approach, and his colleagues designed a new coil configuration that is able to excite neurons at a depth of four centimeters, using the same intensity of current used in standard TMS coils. Instead of a single coil generating a single magnetic field through the brain, Zangen has outfitted a helmet with a number of small coils, each producing a separate magnetic field. As researchers run a standard current through the helmet, the coils, which are connected in a series, produce multiple fields that add up, generating a much stronger magnetic field that goes deeper into the brain before dropping off...
They had good reults in a preliminary study with 50 persons with treatment-refractory depression. Perhaps more interesting, is the potential to broaden the clinical applications:
Meanwhile, Brainsway is designing different coils to tackle brain regions associated with other conditions, such as post-traumatic stress disorder, autism, and drug addiction. Zangen says that in addition to stimulating underactive areas of the brain such as those associated with depression, deep TMS can be used to inhibit brain regions that may be abnormally overactive, such as during addiction.
A quick fix for addiction? Probably not. But if they could reduce or eliminate drug craving, that would be a useful adjunct to traditional abstinence-based treatments.
On the other hand, if it is possible to treat addiction, it might also be possible to cause addiction. That is a bit of a disturbing notion. (In fact, it was anticipated by the science-fiction author Larry Niven.)
But we already have plenty of things that cause addiction, so I don't think this would change the world, really.
As for the treatment of mood disorders, the folks at Brainsway think that their device will be better than regular rTMS, because it can penetrate deep enough to reach the limbic system. This has led them to posit a hypothesis:
Israel's Brainsway stimulates a magnetic remedy for depression
By Nicky Blackburn
February 19, 2006
...The magnetic coil, which is placed on specific areas of the patient's scalp, sends strong directed magnetic pulses through the brain to stimulate the Nucleus Accumbens (the part of the brain responsible for positive stimuli) and the neurons connected to it. "By repeated artificial stimulation of electrical activity created by the coil, we boost the sensitivity of these circuits so they will work more efficiently," says Dr. Hilik Lewkovitch, at Brainsway.
The result is that the next time natural stimulation occurs, such as something pleasant that the brain responds to, the patient will respond more strongly, enjoy it more, and seek to repeat the experience. By intensifying sensitivity this causes the patient to respond normally to the environment...
This hypothesis strikes me as dreadfully simplistic, so I am skeptical of its value. With the human brain, as complex as it is, most initial hypotheses are false. But you have to start somewhere.
The FDA still has to figure out how they are going to evaluate the treatment. It is a novel treatment, so companies that try to get approval from the FDA have to do some guesswork to try to anticipate what will be needed. That is unfortunate, but true.
Despite the bureaucratic hurdles, the Brainsway approach sounds promising. Perhaps they will be able to get that magic p-value of 0.050.
Brain & Behavior
Medicine & Health
Comments
I can just hear the alt-med woo-mongers now: "You see? Magnets do work!"
Posted by: themadlolscientist | June 9, 2008 1:41 PM
Have you seen this? Bloggable?
Posted by: Coturnix | June 25, 2008 3:20 PM