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Structural Changes in the Dementia Brain

Parts of the Brain Shrink

When a person has dementia, parts of their brain become damaged over time (Alzheimer Society 2008). As Alzheimer’s disease progresses, cells within the brain die, and brain tissue is lost. This results in a loss in overall brain size.

The brain is made up of three parts: the cerebrum, the cerebellum, and the brain stem, which receive oxygen and blood through a network of blood vessels. The cortex is part of the outer layer of the cerebellum, which is involved with memory, interpretation of sights and sounds, and thought generation. As a normal part of Alzheimer’s progression, the cortex shrinks, which interferes with those activities. The hippocampus, which is responsible for new memories is most severely damaged (Alzheimer Society 2008, Alzheimer’s Association 2011).

In more advanced stages, the cortex becomes severely damaged, and your loved one may not recognize you or be able to communicate with you.

Plaques and Tangles

Protein clusters, known as “plaques,” gather between nerve cells. Twisted strands of protein, known as “tangles,” gather among dying nerve cells (Alzheimer’s Association 2011). Plaques and tangles begin to form in areas of the brain where memory, learning, and thinking occur, and continue to affect other parts of the brain, damaging the brain and nerve cells (Alzheimer Society 2008).

During mild to moderate stages, they then spread to areas of the brain responsible for communication (speech), and spatial perception. During this time, issues with memory and thought process will typically become apparent, either to the person with dementia, their loved ones, or both. Following these changes, personality and behavior may also become affected (Alzheimer’s Association 2011).

Inflammation

Inflammation is a normal response to trauma, however the level of inflammation in the Alzheimer’s brain is excessive and counter-productive, leading to more cell deaths. Such inflammation causes the death or nerve cells, and may also increase tangles (Alzheimer Society 2008).

Nerve cells shrink

Nerve cells begin to shrink in the part of the brain responsible for memory and thought process, and continue to shrink in the remaining areas of the brain (Alzheimer Society 2008).

References:
Alzheimers Association. 2011. Brain Tour. Available at: http://www.alz.org/braintour/3_main_parts.asp. Accessed April 30th, 2011.
Alzheimer Society. 2008. Changes in the Brain. Available at: http://www.alz.org/braintour/alzheimers_changes.asp. Accessed April 30th, 2011.