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Alzheimer's Disease & Agnosia: Visual Input - DementiaGuide.com
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Alzheimer's Disease


Alzheimer's disease affects the brain's ability to understand and recognize visual input (what is seen). A problem that can result - agnosia - refers to the loss of ability to recognize objects, people, sounds, shapes or smells, when the required sense is not defective.

As a person ages it is natural for them to have difficulty with their vision due to disorders of the eye, such as cataracts or glaucoma . Cataracts, which cause a person's vision to become blurry, occur because of a change in the lens of the eye. Glaucoma causes vision loss and possible blindness due to increasing pressure in the eye. Conditions such as these should be evaluated by a specialist in eye disorders.

However, poor vision can also result from problems in the brain. While, Alzheimer's disease does not cause disorders of the eye, it does cause damage in the areas of the brain that organize visual information. In particular, Alzheimer's disease is known to cause damage the areas known as the occipital and temporal lobes. These areas of the brain send and receive messages to and from the eyes. This miscommunication between what the eyes see and how the brain interprets what the eyes see can cause a person to be able to see and describe an object, but they cannot tell you what the object is. The link between a past experience with an object and the sight of an object is lost. For example, the person can see a face, but cannot recognize that it belongs to their spouse.

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Last updated January 13, 2019
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