Alzheimer's Disease (AD) is a devastating, insidious, and irreversible neurodegenerative disease that affects memory, thinking, and behavior. Alzheimer's mostly affects the population of people that is above the age of 65 but there are people that are younger than 65 that have been found to have the disease. Symptoms can be subtle at first but over time the disease progresses to an extent to which the individual will need assistance with basic needs and be unable to communicate normally. The neurological hallmark finding of AD is the plaque deposits called beta-amyloid and tangles called tau. These deposits disrupt the communication between the nerve cells in the brain. There are three stages of Alzheimer's which are mild (early stage), moderate (middle stage), and severe (late stage). They are distinct in their symptoms. Medications and their mode of action are very important in this disease. Though they might not slow the process of the disease, they can help with the cognitive functioning of the individual.
The fiber tangles within nerve cells (neurofibrillary tangles) and clusters of degenerating nerve endings (neuritic plaques) accumulate and destroy the neurological communications between the cells starting from the hippocampus. Hippocampus is part of the limbic system located in the medial temporal lobe of the brain. Its function is mainly associated with memory, particularly long-term memory and emotional response. This is why you see Alzheimer's presenting as memory loss and difficulty in establishing new memories. As the disease progresses, it continues to destroy parts of the cerebral cortex. The cerebral cortex which is the outer portion of the brain is responsible for thinking and processing sensory information, motor functions, and language processing. The effect the disease has on the cerebral cortex is the reason why people suffering from late-stage Alzheimers have difficulty speaking and walking. The buildup of tangles and plaque leads to cell death. The beta-amyloid accumulates outside the neuron which interferes with the synapses. The tau protein concentrates inside the neuron and blocks the flow of nutrients. With no action potentials to stimulate and no nutrients to support the cell, they eventually die, which is irreversible. In terms of the neurotransmitters that are involved with this condition are acetylcholine and glutamate. Acetylcholine is essential for memory and learning. The deficiency of acetylcholine leads to the individual experiencing problems with memory and functioning. This deficiency is caused by decreased acetylcholine receptors, both nicotinic and muscarinic receptors. Glutamate is an excitatory neurotransmitter and has effects on dementia. It plays a role in information processing, storage, and retrieval.
As previously mentioned, there are 3 stages of Alzheimer's disease and they have very distinctive features. In early Alzheimers, the individual can function independently. They can still dri...
