February 11th, 2010
PTSD Diagnosis, A New Tool – MEG
Prolonged exposure to unremitting stress damages a person’s health. The research is unequivocal (read the science in our Research Library). Mental health impact begins with anxiety. In worst cases, trauma can result. The diagnosis can be elusive because of the strict definition in the DSM-IV-TR (the diagnostic bible) and the reluctance of clinicians to admit what Heinz Leymann knew back in the late 1980’s — work trauma is real. Now comes a potential new neuroscience tool to complement the diagnostic toolkit — MEG. MEG stands for magnetoencephalography. PTSD can be detected with 97% accuracy using this non-invasive, but still experimental, procedure.
MEG measures the magnetic signals produced by the activity of the brain. Signals derive from the net effect of ionic currents flowing in the dendrites of neurons during synaptic transmission (EEG tests also measure these currents though slightly differently). These signals are very small. By comparison, the heartbeat produces a stronger signal. Magnetic resonance imaging (MRI) uses magnetic fields with a signal 3,000,000,000,000,000 stronger than the signal produced by the brain. In order to generate a signal that is detectable, approximately 50,000 active neurons are needed.
The essence of the MEG test is the measurement of the dynamic synchronous neural (bundled) interactions, an essential aspect of the brain function. MEG Dewars (caps) are helmet-shaped and contain as many as 300 sensors, covering most of the head. Then, complex statistical analyses of the data are required to differentiate activity across various areas of the brain to identify specific patterns.
MEG can detect neuronal events with a precision of 10 milliseconds or less, while fMRI, which depends on changes in blood flow, has a lower precision of several hundred milliseconds. MEG also accurately pinpoints sources in primary auditory, somatosensory and motor areas.
Research on brain–machine interfaces has been ongoing for at least a decade. During this period, simultaneous recordings of the extracellular electrical activity of hundreds of individual neurons have been used for direct, real-time control of various artificial devices. Thinking about moving an arm is converted to moving an artificial limb — neuroprosthetics restores mobility in severely paralyzed patients.
MEG has been used to diagnose Alzheimer’s, Parkinson’s disease, epilepsy, schizophrenia, Sjögren’s syndrome, chronic alcoholism, facial pain, and multiple sclerosis. “Communication patterns are very different from disease to disease,” says Dr. Apostolos Georgopoulos from the Brain Sciences Center at the Minneapolis VA Medical Center and University of Minnesota. “So the different diseases create disturbances in the communication that can be used as a fingerprint, a signature, for the disease.”
For years, the diagnosis of PTSD, has been a subjective process involving mental-health professionals conducting structured interviews with patients suffering PTSD-like symptoms.
In a Jan. 2010 issue of the Journal of Neural Engineering, Georgopoulos and his research team reported the successful diagnosis of PTSD using MEG. The Minnesota researchers used MEG to assess 74 U.S. military veterans believed to be suffering from PTSD, along with 250 subjects not thought to be suffering from the condition. Distinctive brain patterns indicating PTSD were found in 72 — or 97.3% — of the 74 people diagnosed with PTSD through the traditional interview process; false positives turned up in 31 of the 250 subjects (12.4%) without PTSD. The findings counter the popular notion that PTSD is not a real disease but a fabricated disorder. The neuronal patterns revealed a distinctive communication pattern, the “PTSD fingerprint.”
Georgopoulos likens the MEG test for PTSD to diabetic blood-glucose monitoring tests to keep their disease under control. “The test is totally safe — there are no magnets, no isotopes — you can do it as frequently as you want,” Georgopoulos says, adding that it also doesn’t require dredging up the traumatic events that generate PTSD. “The whole thing takes literally a minute.”
This most recent application of neuroscience to the world of stressed and traumatized individuals seems profound. However, the question remains about how to distribute the technology and methods to medical practitioners for practical use in the field.
Brain-machine interface: Nature Reviews Neuroscience 10, 530–540 (1 July 2009) | doi:10.1038/nrn2653
MEG detecting diseases: J Neural Eng. 2007 Dec;4(4):349-55. Epub 2007 Aug 27
This entry was posted on Thursday, February 11th, 2010 at 6:24 pm and is filed under Bullying-Related Research, Neuroscience & Genetics, Tutorials About Bullying. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.