*By Clare Wilson/Source: **New Scientist<http://www.newscientist.com/article/dn20348-mind-controls-magnetic-relief-for-depression.html>
Anyone who remembers high-school physics knows that a fluctuating magnetic field can induce an electrical current.
That's the principle behind transcranial magnetic stimulation (TMS), where
an electromagnet is held over the head and pulsed rapidly. Depending on the
frequency of the pulses, this can either enhance or suppress activity in
neurons a few centimetres under the skull.
TMS is seen as one of the safer forms of brain stimulation, as it requires
no surgery. Yet it is not completely risk free: some people experience pain
in the scalp, headaches or facial spasms. More concerning were the 10 cases
of seizures triggered by TMS in the first few years of its use.
Fortunately these became very rare once those administering TMS learned to
limit the intensity and frequency of the stimulation and give patients
regular breaks in treatment. TMS was leapt on as the perfect research tool.
Much knowledge of the brain has come from people who have had a stroke or
head injury - the mental abilities they lack reveal the role of the damaged
area. TMS allows researchers to disable parts of the brain at will in a way
that is completely reversible.
The method has also been tried out in numerous medical conditions and forms
of enhancement. But many of the studies are regarded sceptically, because it
is hard to control for the placebo effect.
Researchers have typically tried to give half the volunteers fake therapy
with the TMS machine turned off, but people often know if they are getting
real treatment or not by the presence or absence of the characteristic physical signs.
TMS has now been approved in the US for treating severe depression. The downside is that patients need to go to a hospital to receive TMS for about 35 minutes a day, five days a week, for four to six weeks. "There's a big schlepp factor," admits Mark George, a neuropsychiatrist at the Medical University of South Carolina.
Last year, however, a group at Emory University in Atlanta found that a
month's worth of treatment could be crammed into a few days with no apparent ill effects. That approach might lead to wider use.
The big drawback of TMS is that at the moment it is only offered at major
hospitals. But US firm Neuralieve is developing a handheld device for people
to use at home for treating migraine. It delivers only a single pulse, but if its safety is proven, who knows how long that will be the case?
VERDICT: Approved for depression, but impractical for less serious illnesses
or enhancement until equipment becomes more portable.
Edited by Lawyer Asad