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Neuropathology of Alzheimer's Disease

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    Neuropathology of Alzheimer's Disease

    Gross Brain Changes

    The following are the gross changes in the brains of the people with Alzheimer’s disease:
    1. Reduced weight of the brain
    2. Reduced cortical volume
    3. Dilated ventricles
    4. Deepening of sulci

    Magnetic Resonance Imaging

    On magnetic resonance imaging, the diagnostically most important finding is atrophy, especially of the medial temporal lobe. It affects the entorhinal cortex the earliest but then it spreads to other regions of the temporal lobe and limbic lobe for example hippocampus, amygdala, and parahippocampus. Later, the pathology extends to parietal lobe and eventually global atrophy. It spares frontal lobes until the late stage. The progression of atrophy occurs in a similar pattern as the progression of the neuropathology.

    Dilated ventricles can show global atrophy, but the most reliable method is a direct measurement of volume. Expansion of the fissures is the indirect, and less reliable way to measure the atrophy. For Alzheimer’s disease, fissures/sulci in the temporal lobe and parietal lobe are more important.

     Parietal atrophy relates to the early onset subtype of Alzheimer’s Dementia.

    It begins in the Entorhinal Cortex. 

    References

    Johnson, K. A., Fox, N. C., Sperling, R. A., & Klunk, W. E. (2012). Brain imaging in Alzheimer disease. Cold Spring Harbor perspectives in medicine, 2(4), a006213. doi:10.1101/cshperspect.a006213

    Alzheimer disease | Radiology Reference Article | Radiopaedia.org. (n.d.). Retrieved January 17, 2020, from https://radiopaedia.org/articles/alzheimer-disease-1

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