Alzheimer's - What Happens In The Brain?
Alzheimer's disease (AD) affects older people's memory, thought and behavior. AD progresses inexorably, causing individuals with the condition to gradually forget knowledge acquired throughout life and interfering with recall of even the simplest among everyday activities. Eventually patients will end up forgetting even the names of their family members. What causes Alzheimer's disease? While the majority of scientists hold the belief that AD is not a normal part of aging, considerable debate still surrounds the issue.
Alzheimer's disease affects a wide part of the brain. It starts by disrupting the way in which electrical charges travel in the cells as well as the action of the neurotransmitters. This causes a disruption in the communication between the nerve cells, thus affecting various functions of the brain.
The other effect Alzheimer's disease has on the brain is that it destroys nerve tissues in all parts of the brain. This eventually results into a dramatically shrunk brain thus affecting almost all functions. The shrinkage is severe in the part of the brain known as the hippocampus - which is responsible for working memory as well as the formulation of new memories. Other noticeable changes in the Alzheimer's brain include the shriveling of the cortex, causing the damage of parts responsible for thinking, remembering and planning.
Under the microscope, it is noticeable that Alzheimer's tissues have but few nerve cells and synapses when compared to a healthy brain. There are also abnormal clusters of fragments of proteins called plaques, that build up between the nerve cells, as well as tangles in dead or dying nerve cells. Tangles are made up of twisted strands of another protein. Both tangles and plaques are considered the main cause of loss of tissue and death of cells in the brain of a person suffering from Alzheimer's. When tangles form in the brain, tracks fall apart and disintegrate, disrupting the supply of nutrients and others to the cells, leading to their death. Plaques on the other hand are mostly formed by beta-amyloid which blocks signals from one cell to another at synapses.
As the Alzheimer's disease progresses, these plaques and tangles will start spreading in the cortex. They start at the areas of the brain dealing with memory, planning, thinking and learning before proceeding to speaking and understanding and areas dealing with sensing the aspects around the individual. At severe stages, the cortex is damaged and wide spread death of cells cause the shrinkage of the brain.
The progression rate of the disease varies from one patient to another, with some living and average of 8 years while others surviving for up to 20 years. Different aspects will also affect the progression of the disease, including existing health conditions and age when the disease is diagnosed.