Magnetic brain scans become more attractive

The first image many of us conjure up when someone mentions
brain scanners—whether for medical diagnosis or basic research—is the sterile
white isolation and intimidating din of a magnetic resonance imaging device.
But for many diseases, the key to better diagnosis may not be looking into
brains, as with MRIs, but looking near
them.

A new study appearing
in the Journal of Neural Engineering suggests
that magnetoencephalography (MEG) can identify the vast majority of people
suffering from post-traumatic stress disorder (PTSD).

In MEG, a helmet surrounding the head measures the tiny magnetic
fields generated by the brain’s electrical activity. This offers distinct
advantages and disadvantages over other scanning methods. For instance, MEG is
noninvasive, unlike positron emission tomography (PET), which requires patients
to ingest a mildly radioactive solution. MEG is also very fast—it works in
about 10 milliseconds—because it measures neural activity directly; MRIs
measure blood flow in the brain instead and take 20 times longer. On the other
hand, readings from MEG offer less spatial resolution than many other scanning
methods and provide less precise information about regions deep inside the
brain.

In the new research, Apostolos
Georgopoulos
, a professor of neuroscience at the University of Minnesota
and a member of the Dana Alliance for
Brain Initiatives
, and his colleagues found that MEG correctly identified at
least 67 of 74 veterans suffering from PTSD, from a group that also included
250 people with no reported neurological or mental health issues. The veterans were
a varied group, with participants both from the current Iraq and Afghanistan
campaigns as well as from World War II and Vietnam.

The researchers also reported that the strength of their
readings corresponded with the severity of symptoms in a PTSD sufferer. In other
words, a MEG test might not just identify who has PTSD but also how damaging
the disorder is and even what treatments might work best.

MEG has shown potential to diagnose other brain symptoms. In
2007, for instance, Georgopoulos and his team reported that MEG could
help detect
multiple sclerosis, Alzheimer’s disease, schizophrenia,
Sjögren’s syndrome, chronic alcoholism and facial pain. And earlier this month,
we reported on a small
study that used MEG to identify children with autism
.

As we mentioned in that post, small tests such as the PTSD
study aren’t useful in the clinic until they have been confirmed in more
expansive tests with more diverse sets of people. Still, many neurological
disorders, including a large percentage of PTSD cases, are difficult and
time-consuming to diagnose. Objective detection methods such as brain scans could
dramatically shorten that process, as well as reduce uncertainty about the
accuracy of a diagnosis or the severity of a particular case.

For soldiers, who are at high risk for PTSD, this is
crucial; their final diagnosis can drastically alter what jobs they are
expected to do, where they are sent during their next deployment and what kind
of benefits they can receive. In the most extreme cases, a doctor’s finding might
mean the difference between re-entering a dangerous war zone and safely recovering
from trauma on U.S. soil. For those kinds of cases, a fast, efficient way to
assess PTSD can’t come fast enough.

—Aalok Mehta

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