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How do amyloid plaques and tau tangles affect the brain in Alzheimer disease?
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The routine monitoring of blood pressure levels is an important part of assessing an individual's health. Blood pressure provides information about the amount of blood in circulation and about heart function and thus is an important indicator of disease.
In Alzheimer disease, the brain is characterized by the presence of two primary types of lesions that are believed to interfere with normal cellular functioning:
- Neuritic plaques: Also known as amyloid plaques, these consist of deposits of a sticky protein called amyloid beta surrounded by deteriorating neuronal material. Amyloid beta is derived from the amyloid precursor protein, a normal component of nerve cells.12
- Neurofibrillary tangles: These are twisted fibers of a protein called tau located within neurons. While tau normally occurs in neurons, it can become incorrectly processed, causing the molecules to clump together into tangles.12
While these lesions are hallmarks used to diagnose the disease during autopsy, it remains scientifically unclear whether they are a primary cause or a consequence of the disease process. Their accumulation is associated with the loss of neurons and diminished levels of essential neurotransmitters, which ultimately leads to the cognitive and physical decline observed in patients.12