They are believed to produce a neurotoxic effect and are akin to functionless brain scar tissue.
3. Neurofibrillary Tangles. The neurofilaments of a neuron are the skeletal structures of the cell and serve as the transport system for components within the neuron. When these become malformed the cells cannot function properly nor send messages to other neurons. Tangles also lead to cell death.
Third, there is no cure for AD. AD is progressive and is 100% fatal (although many elderly patients may die from other complications). There are many conditions that mimic dementia and are reversible. The average expected lifespan for a person diagnosed with early AD is about seven to eight years, but the course can last anywhere from one to twenty years (Molsa, Marttila, & Rinne, 1995; Ropper & Samuels, 2009).
Fourth, there is no way to predict for certain if a person will develop AD. Recently, there have been a number of studies using PET scanning or other brain scanning techniques that demonstrate promise in identifying individuals at risk to develop AD, but all these at risk individuals will not develop dementia (Ropper & Samuels, 2009).
Fifth, AD appears to have several subtypes which do not have the same progression in every individual (Ropper & Samuels, 2009).
Treatment for AD
There is no cure for AD but there have been medications developed that are hypothesized to slow the course of early AD and one class of medications hypothesized to accomplish this in the later stages. Medications are (Miller & Boeve, 2009; Sadock & Sadock, 2007):
1. Cholinesterase Inhibitors. These are based on the "Cholinergic Hypothesis of AD" from early studies demonstrating a reduction of the neurotransmitter acetylcholine in the brains AD patients. Acetylcholine is also believed to be important in memory. When neurotransmitters are released and have performed their function they can be reabsorbed chemically broken down. Cholinesterase is a by-product of the breakdown process of acetylcholine. Cholinesterase inhibitors reduce the rate at which acetylcholine is broken down. The most commonly used cholinesterase inhibitors approved for AD include Aricept, Razadyne, and Exelon. Most of these medications are hypothesized to be effective in the earlier stages of AD; Aricept has some support for its effectiveness in later stages.
2. NMDA Receptor Antagonists. These work on glutamate, an excitatory neurotransmitter. When glutamate neurons become overly stimulated for extended periods they may die through a process known as excitotoxicity. The NMDA neuron receptor is a glutamate receptor. These drugs bind to these receptors and inhibit firing of the glutamate neuron. Memantine is the drug in this class also known as Namenda, Akatinol, Axura, Memox and Abixa. These drugs are often used for the later stages of AD, often combined with Aricept.
3. Behavioral Problems in AD. These problems range from apathy, depression, aggression, and hallucinations and delusions. Such issues are commonly treated with psychotropic medications.
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