Reading Your Mind: The Future of Brain Imaging

Neurodegenerative disorders are among those diseases where diagnostic technologies are currently outpacing treatment options. And that is likely to be the case for some time, as screening technologies continue to rapidly improve. We have a precedent in Huntington’s disease, the neurodegenerative disorder that killed Woody Guthrie; the genetics of Huntington’s, for which there is still no prevention or treatment, were worked out in the 1970s [needs check] and it was possible to test who was going to develop it. According to studies that have examined how people make decisions about testing, only 15-20% of individuals at risk for Huntington’s have actually sought out a test.

The fundamental question remains: what good is a diagnosis without a treatment? Unlike HIV, there is no public health concern about transmission. So what are the reasons people might have for learning that they are likely to develop Alzheimer’s or Parkinson’s or ALS (Lou Gehrig disease) if there are not yet effective treatments?

Preparation, whether it is emotional, psychological or financial or a combination of all three, is likely to loom as the largest factor. But that applied to Huntington’s too and there were not many takers. Will that change and if so, why? There is certainly more optimism that Alzheimer’s and Parkinson’s will soon have treatments that will slow the progression of the disease. We are likely to find out quite soon. LESS

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It used to require an autopsy to positively identify a brain that had been ravaged by plaques and tangles of Alzheimer’s. That is no longer strictly the case, but there is still no single, definitive test that medical experts agree on for diagnosing the onset and progression of the disease. And yet, like Supreme Court Justice Stewart said about pornography, we know it when we see it. Doctors can reliably detect Alzheimer’s and families are probably even more sensitive to the changes that accompany the early stages, though family members certainly have reason to ignore those signs.

Current diagnoses of Alzheimer’s relay on physical exams, lab tests, cognitive evaluations, both short tests that can be done in 10 minutes and more extensive neuropsychological tests. Diagnostic screening that is showing promise and will very likely play a greater role in the future involves an array of braining imaging technologies, includes computerized tomography (CT), which is good at ruling out tumors, strokes and head injuries; magnetic resonance imaging (MRI), which may be used to measure volume and determine whether brain tissue is shrinking; and positron emission tomography (PET), which shows particular potential in identifying tell-tale plaques.

Another approach to diagnostic screening that is being developed is measuring levels of key proteins or protein patterns in blood or spinal fluid. And progress is also being made untangling the genetics of Alzheimer’s. One of the first pieces to be put together in this puzzle applies to only very few people, but it has shed light on important aspects of the disease. Researchers discovered that there were three rare genetic syndromes that cause people to develop Alzheimer’s disease very early, usually before they age 60. A mutation in a single gene was responsible in each version of this early onset of the disease.

That is certainly progress in the understanding of the genetic basis of Alzheimer’s, but these mutations account for only a small percentage of cases. If someone has one of these mutations, it is a virtual guarantee that you will develop Alzheimer’s. Researchers have also found a fourth gene that comes in three different forms. One of those forms puts individuals at higher risk of Alzheimer’s but does not guarantee they will develop the disease. In fact, over half the people who carry this version of the gene will not develop Alzheimer’s and many people who don’t carry that version of the gene will. LESS

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One of the most important reasons to accurately diagnose a neurological disorder, even when treatment options are limited, is that neurologic disorders often produce similar symptoms. (The symptoms of Parkinson's disease, for example, can be caused by other neurological disorders, as well as by toxins, head trauma, and even some medications.) With some of these disorders, the progress is very quick and disability is total; in others, the disease progresses very slowly. These differences can have profound impacts on patients and their families.

Many of the screening and diagnostic tools being used (or developed) are similar to the ones being used to detect Alzheimer’s, such as thorough physical exams, medical histories, and neurological evaluations, as well as brain imaging using CT, MRI and PET scans. With Parkinson’s, however, MRI and CT scans appear normal. Still, there is hope that scanning technologies, coupled with other tests, will prove to be helpful. LESS

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