I learned this today. No one seems to know the definite cause of Alzheimer’s Disease but it seems to be connected with the buildup of amyloid plaque in the brain, entanglement in the neurons, and inflammation of neurons.
Alzheimer’s Disease was named after Dr. Alois Alzheimer. The disease had obviously existed for thousands of years, but Dr. Alzheimer was the first person to study it. In 1901, he followed a German lady until her death in 1906 and wrote about her condition. When she died he analyzed her brain and found many clumps and tangled fibers.
There are approximately 50 million people in the world suffering from Alzheimer’s at any one time. The majority of those people are over 75 years old, but the disease affects people of any age. Early onset Alzheimer’s can start pretty much any time after the age of about 30.
Alzheimer’s is a disease that progressively gets worse, however, it is not a fatal disease. Often, complications of the disease are what kill people, not the disease itself. The disease stops sufferers from being able to go about normal life, even to the point where they cannot swallow properly or move a lot. A big killer of Alzheimer sufferers is aspiration pneumonia. This is when people can’t swallow properly and food goes down into the windpipe and causes infection in the lungs, leading to pneumonia.
So, what causes the disease? That turns out to be a tough question to answer. Scientists can tell how a brain with Alzheimer’s is different to a brain without Alzheimer’s, and they can make a guess as to why this happens, but they do not know for certain. They also don’t know why it starts to happen when people get older.
The predominant current theories are that it is caused by the buildup of proteins in the brain. Specifically, a protein called beta-amyloid and another called tau.
Beta-amyloid is a protein that is created in many cells, but particularly in the brain. It is created in the synapses of the brain. The synapses use an alpha-beta precursor protein that breaks down and produces beta-amyloid protein. This protein is usually cleared out of the brain, but in people with Alzheimer’s it starts to build up and forms plaque. It is toxic and it collects between the neurons, disrupting cell functions and killing off neurons.
The second protein is called tau. The tau protein exists inside neurons, and it is used to stabilize microtubes inside the neurons that channel nutrients and molecules to where they need to be. Alzheimer’s disease causes chemical changes in these tau proteins, and they stop doing the job they are supposed to do and stick to other tau proteins to make chains. These chains form tangles inside the neurons and block nutrients coming in and stop the neurons communicating. The tau protein and the beta-amyloid protein seem to have some kind of a connection in people with Alzheimer’s because the tau tangles and the amyloid both build up but once the amyloid builds up to a certain level, the tau makes a jump and spreads through the whole brain.
A third thing found in the brains of Alzheimer sufferers is chronic inflammation. In the brain there are two types of cells called microglia and astrocytes. Their job is to remove waste products from the brain, such as beta-amyloid protein. They find the waste products, engulf them, and metabolize them. For some reason, in people with Alzheimer’s, these cells move to the location of where the waste products are, but then they just stop. They gather around the neurons that they are supposed to be protecting and release toxic chemicals instead.
The combination of these three things leads to massive neuron death in the brains of diseased people. The brains of people in the later stages of Alzheimer’s disease are drastically smaller than the brains of healthy people of a similar age.
One of the problems that researchers have is that just because the brains of people who have Alzheimer’s exhibit these three features, it is difficult to say whether they cause the disease or if the disease causes them.
There is no cure available for Alzheimer’s and the damage is irreversible. There are medicines that can slow down the progress, but nothing can be done to stop it. And Alzheimer’s disease is not only hard on the people who have it, but more so on their caregivers and the family that have to watch the people they loved disappear.
So, Alzheimer’s disease might be caused by the build up a protein called beta-amylose that blocks synapses, a protein called tau that tangles up the inside of neurons, and a cell called microglia that don’t do the job they are supposed to. And this is what I learned today.
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PBy National Institutes of Health – https://commons.wikimedia.org/w/index.php?curid=16969598
Sources:
https://www.nhs.uk/conditions/alzheimers-disease/causes/
https://www.nia.nih.gov/health/what-causes-alzheimers-disease
https://www.nia.nih.gov/health/what-alzheimers-disease
https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease
https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease
https://www.alzheimers.gov/alzheimers-dementias/alzheimers-disease
https://en.wikipedia.org/wiki/Alzheimer%27s_disease