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  • Transcriber: TED Translators admin Reviewer: Ivana Korom

  • We're now becoming aware of a significant relationship

  • between sleep and Alzheimer's disease.

  • [Sleeping with Science]

  • Now, Alzheimer's disease is a form of dementia

  • typified usually by memory loss and memory decline.

  • And what we've started to understand

  • is that there are several different proteins

  • that seem to go awry in Alzheimer's disease.

  • One of those proteins is a sticky, toxic substance

  • called beta-amyloid that builds up in the brain.

  • The other is something called tau protein.

  • How are these things related to sleep?

  • Well first, if we look at a large-scale epidemiological level,

  • what we know is that individuals

  • who report sleeping typically less than six hours a night,

  • have a significantly higher risk

  • of going on to develop high amounts

  • of that beta-amyloid in their brain later in life.

  • We also know that two sleep disorders,

  • including insomnia and sleep apnea, or heavy snoring,

  • are associated with a significantly higher risk

  • of Alzheimer's disease in late life.

  • Those are, of course, simply associational studies.

  • They don't prove causality.

  • But more recently,

  • we actually have identified that causal evidence.

  • In fact, if you take a healthy human being

  • and you deprive them of sleep for just one night,

  • and the next day, we see an immediate increase

  • in that beta-amyloid,

  • both circulating in their bloodstream,

  • circulating in what we call the cerebrospinal fluid,

  • and most recently, after just one night of sleep,

  • using special brain-imaging technology,

  • scientists have found that there is an immediate increase

  • in beta-amyloid directly in the brain itself.

  • So that's the causal evidence.

  • What is it then about sleep

  • that seems to provide a mechanism

  • that prevents the escalation

  • of these Alzheimer's-related proteins?

  • Well, several years ago,

  • a scientist called Maiken Nedergaard

  • made a remarkable discovery.

  • What she identified was a cleansing system in the brain.

  • Now, before that,

  • we knew that the body had a cleansing system

  • and many of you may be familiar with this.

  • It's called the lymphatic system.

  • But we didn't think that the brain had its own cleansing system.

  • And studying mice,

  • she was actually able to identify a sewage system within the brain

  • called the glymphatic system,

  • named after the cells that make it up,

  • called these glial cells.

  • Now, if that wasn't remarkable enough,

  • she went on to make two more incredible discoveries.

  • First, what she found is that that cleansing system in the brain

  • is not always switched on in high-flow volume

  • across the 24-hour period.

  • Instead, it was when those mice were actually sleeping,

  • particularly when they went into deep non-REM sleep,

  • that that cleansing system kicked into high gear.

  • The third component that she discovered,

  • and this is what makes it relevant

  • to our discussion on Alzheimer's disease,

  • is that one of the metabolic by-products,

  • one of the toxins that was cleared away during sleep,

  • was that sticky, toxic protein, beta-amyloid,

  • linked to Alzheimer's disease.

  • And just recently, scientists in Boston have discovered

  • a very similar type of pulsing, cleansing brain-mechanism

  • in human beings as well.

  • Now, some of this discussion may sound perhaps a little depressing.

  • We know that as we get older in life,

  • our sleep seems to typically decline,

  • and our risk for Alzheimer's generally increases.

  • But I think there's actually a silver lining here,

  • because unlike many of the other factors

  • that are associated with aging and Alzheimer's disease,

  • for example, changes in the physical structure of the brain,

  • those are fiendishly difficult to treat

  • and medicine doesn't have any good wholesale approaches right now.

  • But that sleep is a missing piece

  • in the explanatory puzzle of aging and Alzheimer's disease

  • is exciting because we may be able to do something about it.

  • What if we could actually augment human sleep

  • and try to improve the quality

  • of that deep sleep in midlife,

  • which is when we start to see the decline in deep sleep

  • beginning to happen.

  • What if we could actually shift

  • from a model of late-stage treatment in Alzheimer's disease

  • to a model of midlife prevention?

  • Could we go from sick care to actually healthcare?

  • And by modifying sleep,

  • could we actually bend the arrow

  • of Alzheimer's disease risk down on itself?

  • That's something that I'm incredibly excited about

  • and something that we're actively researching right now.

Transcriber: TED Translators admin Reviewer: Ivana Korom

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What's the connection between sleep and Alzheimer's disease? | Sleeping with Science, a TED series

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    林宜悉 posted on 2020/10/26
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