Can a Brain Scan Predict Alzheimer's?

Contributed by: Dennis Fortier, President, Medical Care Corporation

There is a lot of recent press suggesting that a brain scan may be useful in predicting Alzheimer's disease.

The excitement has been generated by a new study showing that a good read on the size and shape of particular portions of the brain, can be useful in predicting which patients, among a group with subtle symptoms of memory loss, will develop Alzheimer's disease.

The journalists at MSNBC, provide a good example of how the concept of "predicting" is frequently misused in the press, when they are actually writing about "identifying".  Almost invariably, the confusion between predicting and identifying Alzheimer's, is coupled with the misleading notion that subtle symptoms of memory loss sometimes "progress" to Alzheimer's.

I want to untangle these various notions, and offer a clear summary of what I think these journalists are trying to convey.

Mild Cognitive Impairment
When a person has mild symptoms of memory loss that are more severe than those we expect with normal aging, but not severe enough to qualify as dementia, we describe their condition as "mild cognitive impairment" (MCI).  By definition, MCI is not a part of normal aging.  This means that it is caused by some underlying medical condition such as vascular disease, a  thyroid disorder, depression or a number of other causes.  It might also be due to early stage Alzheimer's disease.

Predicting vs. Identifying
The key point is, if you have MCI due to Alzheimer's disease, then you have Alzheimer's disease.  There is no need to predict, only to identify.  There is no concept of "progression", the disease is already present.

So, the recent study that has generated much press, is a good study with a potentially valuable conclusion.  When a person has mild cognitive symptoms that we call MCI, and a physician must diagnose the correct cause of the symptoms in order to administer appropriate treatment, the ability to identify Alzheimer's disease  as the cause (or not the cause), is very important.  If a scan of brain structure is valuable in this regard, then we have gotten better at diagnosing this terrible disease.

We have not, however, found a new way to predict anything.  Only a new way to better identify a disease that is already present.


  1. Brain Scan and spinal fluid test... here is a spinal tap that's close to completion

    The American Business Journal: Amorfix Life Sciences: 01 April, 2011 02:52:00
    Mississauga, Ontario-based Amorfix Life Sciences has announced that is developing a new diagnostic test that is able to measure clumped protein fragments, called aggregated beta amyloid, in human cerebral spinal fluid which may indicate the presence of Alzheimer’s disease, making it easier to accurately diagnose.
    Amorfix Life Sciences is a product development company focused on diagnostics and therapeutics for misfolded protein diseases including Alzheimer’s disease, cancers and ALS. The company is forging new ground in the ability to develop diagnostics using unique regions, or Disease Specific Epitopes, which, once identified, can be targeted in the pursuit of treatment and therapeutics.
    Currently, the only definitive diagnosis for Alzheimer’s is a post-mortem examination of brain tissue.The Amorfix test is conducted on the cerebral spinal fluid from living patients, representing a significant step forward in early detection and subsequent treatment of the disease. “ The breakthrough was we measure levels of aggregated beta amyloid on the cerebral spinal fluid on patients who were diagnosed with Alzheimer’s and compared those levels to levels from aged matched control subjects who did not have Alzheimer’s disease and found that there was a difference “ , says Dr. Robert Gundel, Amorfix President and CEO.
    “ The importance of our work and its real significant is the measurement of the aggregated beta amyloid, which leads to plaque formation in the brain” says Gundel. Our hope is to one day be able to use this test on patients showing early signs of dementia in order to predict which patients may progress rapidly into the disease and which may not.”

  2. Thanks for this comment. I wrote about the spinal fluid research earlier (you can search this blog for "spinal fluid" and find several entries). You can see the same confusion between "predicting" and "identifying" in that coverage as well.

  3. I'm glad to have found your blog and read this post. The media sees itself as a watchdog, but when it comes to health, it desperately needs its own watchdogs. As a freelance writer who specializes in health and senior issues, I'm a member of said media. I look forward to more posts so I can continue striving to watchdog my own self. :-)