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
