The diagnostic signposts marking neurological illness are often obscured by the complex machinery of the brain. Better neuroimaging techniques may soon allow doctors to pierce through the veil of gray matter to ascertain which tangle of neurons will lead to failing memory, lost motor function, or death. While the increasing sensitivity of MRI, fMRI, and PET scans allows diseases to be pinpointed with greater accuracy, sometimes long before symptoms arise, they aren’t foolproof. Here’s a selective list of disorders for which brain scans hold some promise:
Autism: Last week, British scientists reported in the Journal of Neuroscience that they were able to use MRI scans to spot autism with 90% accuracy in a small, preliminary study of 40 adults. The authors caution, however, that the procedure has not been tested in children yet and is still an exploratory technique.
Alzheimer’s disease: Citing the improvement of brain scan techniques, experts recently revised the criteria for Alzheimer’s disease, creating a category called “preclinical Alzheimer’s” for patients that have yet to exhibit severe memory loss. One of the procedures that could one day allow doctors to diagnose preclinical Alzheimer’s are PET scans, which use gamma rays to create a three-dimensional picture of brain activity. The scan can detect clumps of amyloid beta protein forming the plaques in the brain that are thought to be an early sign of Alzheimer’s.
Schizophrenia: There’s a spate of articles in the literature on how MRIs can be used to diagnose schizophrenia by identifying “grey matter loss”. But, as Robert Whitaker of Psychology Today explains, data from this population of patients is notoriously difficult to interpret, not least because long-term use of antipsychotics may influence the brain.
Stroke: Before doctors can treat a stroke patient, it’s important to figure out what kind of stroke they’re dealing with. An MRI allows doctors to differentiate between ischemic (caused by a blood clot in the brain) and hemorrhagic (where a blood vessel bursts in the brain). Last month, the American Academy of Neurology said that MRIs should replace CT scans, the current standard.
Parkinson’s disease: While MRIs and CT scans are unable to conclusively identify Parkinson’s disease, they’re often an important first step in ruling out alternative diagnoses, like brain tumors or stroke.
The list of clinical applications of brain scans continues to grow, with other studies focusing their potential to diagnose post traumatic stress disorder and obsessive compulsive disorder. The tests still seem far from ready for use in the clinic, but their noninvasive nature makes them an attractive tool for consideration. What do you see as the promise and pitfalls of brain scans as diagnostic tools?
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