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Alzheimer's Disease: Where it Starts in the Brain - DementiaGuide.com
   
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Alzheimer's Disease

Where it Starts in the Brain

Alzheimer's Disease results in destruction of the brain's nerve cells and tissue loss. It is believed that this damage is caused by plaques (abnormal protein built between nerve cells) and tangles (twisted strands of proteins). Over the course of the disease, the brain decreases dramatically in size. These changes will cause noticeable symptoms which can be explained by damage having occurred to certain parts of the brain.

Alzheimer's disease begins deep in the brain with a set of structures known as the limbic system . As cholinergic neurons become lost or damaged, pathways to and from the limbic system begin to shut down. The limbic system is important for memory , behaviour and emotions. The result of damage to the limbic system can include symptoms such as misplacing or losing common objects, suspiciousness, irritability, depression and anxiety.

Some other important brain structures affected by Alzheimer's disease are the hippocampus , the amygdala, the parietal lobes, and the frontal lobes. The hippocampus is a "sea-horse" shaped structure that is involved with the processing of memory, both visual and verbal. The amygdala is responsible for the experience and expression of emotions. This explains why memory loss and personality changes are some of the earlier signs of Alzheimer's disease. The parietal lobes are involved with sequencing of events such as dressing and cooking, and can lead to symptoms such as the incorrect use of words, problems understanding speech, and getting lost. The frontal lobes are involved with initiation and planning actions as well as social judgment. Problems in this area of the brain often result in changes such as the person being uninterested and uncaring toward others and decreased participation in previously enjoyed activities.

As the disease progresses, pathways leading to the outer surfaces of the brain become affected. The outer surfaces of the brain are known as the cortex . These outer surfaces are responsible for many different functions such as language, reasoning, orientation, personality and sensory information.

See Also:
Symptom Library > Physical Changes > Sensory Input
Symptom Library > Personality Changes > Personality Changes
Symptom Library > Behaviour > Disorientation to Place
Symptom Library > Memory & Language > Language Difficulty/Expression/Word Finding
About Dementia > Alzheimer's Disease > Early Signs
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Last updated December 6, 2017
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