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  • Every four seconds,

  • someone is diagnosed with

  • Alzheimer's disease.

  • It's the most common cause of dementia,

  • affecting over 40 million people worldwide,

  • and yet finding a cure is something that still

  • eludes researchers today.

  • Dr. Alois Alzheimer, a German psychiatrist,

  • first described the symptoms in 1901

  • when he noticed that a particular hospital patient

  • had some peculiar problems,

  • including difficulty sleeping,

  • disturbed memory, drastic mood changes,

  • and increasing confusion.

  • When the patient passed away,

  • Alzheimer was able to do an autopsy

  • and test his idea that perhaps

  • her symptoms were caused by irregularities

  • in the brain's structure.

  • What he found beneath the microscope

  • were visible differences in brain tissue

  • in the form of misfolded proteins

  • called plaques,

  • and neurofibrillary tangles.

  • Those plaques and tangles work together

  • to break down the brain's structure.

  • Plaques arise when another protein

  • in the fatty membrane surrounding nerve cells

  • gets sliced up by a particular enzyme,

  • resulting in beta-amyloid proteins,

  • which are sticky and have a tendency

  • to clump together.

  • That clumping is what forms the things

  • we know as plaques.

  • These clumps block signaling

  • and, therefore, communication

  • between cells, and also seem to trigger

  • immune reactions that cause the destruction

  • of disabled nerve cells.

  • In Alzheimer's disease, neurofibrillary tangles

  • are built from a protein known as tau.

  • The brain's nerve cells contain a network of tubes

  • that act like a highway for food molecules

  • among other things.

  • Usually, the tau protein ensures that these tubes

  • are straight, allowing molecules

  • to pass through freely.

  • But in Alzheimer's disease,

  • the protein collapses into twisted strands or tangles,

  • making the tubes disintegrate,

  • obstructing nutrients from reaching the nerve cell

  • and leading to cell death.

  • The destructive pairing of plaques and tangles

  • starts in a region called the hippocampus,

  • which is responsible for forming memories.

  • That's why short-term memory loss

  • is usually the first symptom of Alzheimer's.

  • The proteins then progressively invade

  • other parts of the brain,

  • creating unique changes that signal

  • various stages of the disease.

  • At the front of the brain,

  • the proteins destroy the ability to process logical thoughts.

  • Next, they shift to the region that controls emotions,

  • resulting in erratic mood changes.

  • At the top of the brain,

  • they cause paranoia and hallucinations,

  • and once they reach the brain's rear,

  • the plaques and tangles work together

  • to erase the mind's deepest memories.

  • Eventually the control centers governing

  • heart rate and breathing are overpowered as well

  • resulting in death.

  • The immensely destructive nature of this disease

  • has inspired many researchers to look for a cure

  • but currently they're focused on slowing its progression.

  • One temporary treatment

  • helps reduce the break down of acetylcholine,

  • an important chemical messenger in the brain

  • which is decreased in Alzheimer's patients

  • due to the death of the nerve cells that make it.

  • Another possible solution is a vaccine

  • that trains the body's immune system to attack

  • beta-amyloid plaques before they can form clumps.

  • But we still need to find an actual cure.

  • Alzheimer's disease was discovered

  • more than a century ago,

  • and yet still it is not well understood.

  • Perhaps one day we'll grasp

  • the exact mechanisms at work behind this threat

  • and a solution will be unearthed.

Every four seconds,

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B2 TED-Ed alzheimer alzheimer disease brain disease nerve

【TED-Ed】What is Alzheimer's disease? - Ivan Seah Yu Jun

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    阿多賓 posted on 2014/04/17
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