Alzheimer’s disease is the most common form of dementia, in which people become forgetful and confused, usually starting in older age. People with Alzheimer’s have a build-up of two kinds of protein clumps in the brain: amyloid and tau. These seem to start forming in our memory centres, two small curved structures on either side of the head called the hippocampi, before spreading all over the brain.
For a long time, we thought that these proteins, particularly amyloid, were the root cause of the disease, but many experimental therapies that attacked them in some way have failed to reverse or even slow the condition’s progression. And autopsies often reveal the proteins in people who showed no signs of dementia when they were alive. So some suspect that the protein build-up is more of a side-effect of Alzheimer’s than the root cause.
What could be the real trigger? One idea is that it could be the bacteria involved in gum disease. These microbes are found more often in brain samples from people with the condition, and they trigger Alzheimer’s when injected into mice. A vaccine and an anti-bacterial treatment are in the works.
Another school of thought is that Alzheimer’s is caused by failure of the brain’s sewage disposal system. This “glymphatic” system, a network of fine tubes that drain fluid out of the brain, kicks in when we sleep, and people with Alzheimer’s do often have sleep problems.
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Then there are more off-the wall ideas, such as that it is caused by air pollution or that it is a form of diabetes affecting the brain.
But for now, there are sadly no medicines that can cure or prevent the condition. The best we can do is reduce our chances of getting it by adopting healthy lifestyles, in other words not smoking and making sure we eat well and get enough sleep and exercise.
