Imaging Brain Changes in Alzheimer’s Disease

Alzheimer’s research aims to decrease some of the uncertainty surrounding causes, diagnosis, and treatment of the disease.  Many researchers believe that an important aspect of treatment will involve identifying the disease early and treating those early changes in the brain.

Beta-amyloid plaques are aggregates found in the brain of Alzheimer’s patients. Historically, these plaques were only identifiable upon autopsy.

A beta-amyloid plaque

Recently, better techniques for imaging these plaques have been developed.  As techniques improve, more information about the effects of the development of the disease on the brain can be gathered.

In a recent paper in Brain: A Journal of Neurology (published online February 9th), Gael Chetelat and colleagues use imaging techniques to more fully recognize early brain changes in Alzheimer’s progression and how those changes relate to memory decline.  Using magnetic resonance imaging (MRI), the researchers image and recognize a portion of the brain called grey matter.  They also use positron emission tomography (PET) to visualize a tracer that marks beta-amyloid deposits.  They aim to relate the breakdown of brain matter and the location of beta-amyloid plaques to the degree of memory loss in patients in the pre-dementia stage of Alzheimer’s disease.

The researchers find that memory performance of patients in the pre-dementia stage relates to two changes in the brain.  The first change is increased beta-amyloid deposition, specifically in the temporal neocortex.  The temporal neocortex is part of the outer layer of the brain located on either side, and it plays a critical role in visual processing, storage of language, and memory.

Labeling of temporal beta-amyloid deposition (left) and location of reduced grey matter in the hippocampus (right)

The second change in the brain is a decrease in grey matter in the hippocampus.  The hippocampus is located inside the brain structure with mirror-image halves in the right and left sides of the brain, and it is important in navigation and long-term memory.  The authors suggest that these insults to the brain structure should be considered separately as researchers look for possible targets of therapies.

The prospect of imaging specific changes in brain structure is exciting.  If these changes can be related to future Alzheimer’s progression or other forms of memory loss (which the authors caution cannot be done from their study), early identification of these insults may allow time for intervention and treatment that can slow or stop memory loss.  Knowledge of the specific locations of the insults as well as improvements in the techniques available to image the brain will be invaluable advances in the fight against dementia and Alzheimer’s.

Beta-amyloid photo here.  MRI photos from Chetelat study here.

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4 responses to “Imaging Brain Changes in Alzheimer’s Disease

  1. Interesting stuff… Are there more Alzheimer’s cases now because we’re living longer? What are some environmental risks? The imaging techniques are also of great interest!

    • Thanks for the comment, Joe! Alzheimer’s cases are definitely increasing with longer life spans. An estimated 5 million people in the U.S. currently have the disease, and with baby boomers aging, scientists estimate that number could reach 8 million by 2030. As for environmental risks, nutritional deficiencies, high-cholesterol diets and smoking have been linked to increased risks of Alzheimer’s. Also, education appears to lower the risk of developing the disease, but the reasons behind these correlations are still being studied.

  2. I didn’t know Alzheimer’s attacked grey matter as well as the hippocampus — interesting stuff. Did they indicate which would be a priority for studying further or is it too early to tell?

  3. Nice use of images to illustrate a point, Caroline. And I think your writing is becoming more conversational which I like and want to encourage further. This is exactly the kind of post that should reach an audience outside the science savvy. Can’t wait to see what you do with budget issues in medical science.

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